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In Vitro, In Vivo and In Silico Characterization of a Novel Kappa-Opioid Receptor Antagonist. Pharmaceuticals (Basel) 2022; 15:ph15060680. [PMID: 35745598 PMCID: PMC9229160 DOI: 10.3390/ph15060680] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 05/20/2022] [Accepted: 05/24/2022] [Indexed: 12/04/2022] Open
Abstract
Kappa-opioid receptor (KOR) antagonists are promising innovative therapeutics for the treatment of the central nervous system (CNS) disorders. The new scaffold opioid ligand, Compound A, was originally found as a mu-opioid receptor (MOR) antagonist but its binding/selectivity and activation profile at the KOR and delta-opioid receptor (DOR) remain elusive. In this study, we present an in vitro, in vivo and in silico characterization of Compound A by revealing this ligand as a KOR antagonist in vitro and in vivo. In the radioligand competitive binding assay, Compound A bound at the human KOR, albeit with moderate affinity, but with increased affinity than to the human MOR and without specific binding at the human DOR, thus displaying a preferential KOR selectivity profile. Following subcutaneous administration in mice, Compound A effectively reverse the antinociceptive effects of the prototypical KOR agonist, U50,488. In silico investigations were carried out to assess the structural determinants responsible for opioid receptor subtype selectivity of Compound A. Molecular docking, molecular dynamics simulations and dynamic pharmacophore (dynophore) generation revealed differences in the stabilization of the chlorophenyl moiety of Compound A within the opioid receptor binding pockets, rationalizing the experimentally determined binding affinity values. This new chemotype bears the potential for favorable ADMET properties and holds promise for chemical optimization toward the development of potential therapeutics.
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2
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Puls K, Schmidhammer H, Wolber G, Spetea M. Mechanistic Characterization of the Pharmacological Profile of HS-731, a Peripherally Acting Opioid Analgesic, at the µ-, δ-, κ-Opioid and Nociceptin Receptors. Molecules 2022; 27:919. [PMID: 35164182 PMCID: PMC8840597 DOI: 10.3390/molecules27030919] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/24/2022] [Accepted: 01/26/2022] [Indexed: 02/01/2023] Open
Abstract
Accumulated preclinical and clinical data show that peripheral restricted opioids provide pain relief with reduced side effects. The peripherally acting opioid analgesic HS-731 is a potent dual μ-/δ-opioid receptor (MOR/DOR) full agonist, and a weak, partial agonist at the κ-opioid receptor (KOR). However, its binding mode at the opioid receptors remains elusive. Here, we present a comprehensive in silico evaluation of HS-731 binding at all opioid receptors. We provide insights into dynamic interaction patterns explaining the different binding and activity of HS-731 on the opioid receptors. For this purpose, we conducted docking, performed molecular dynamics (MD) simulations and generated dynamic pharmacophores (dynophores). Our results highlight two residues important for HS-731 recognition at the classical opioid receptors (MOR, DOR and KOR), particular the conserved residue 5.39 (K) and the non-conserved residue 6.58 (MOR: K, DOR: W and KOR: E). Furthermore, we assume a salt bridge between the transmembrane helices (TM) 5 and 6 via K2275.39 and E2976.58 to be responsible for the partial agonism of HS-731 at the KOR. Additionally, we experimentally demonstrated the absence of affinity of HS-731 to the nociceptin/orphanin FQ peptide (NOP) receptor. We consider the morphinan phenol Y1303.33 responsible for this affinity lack. Y1303.33 points deep into the NOP receptor binding pocket preventing HS-731 binding to the orthosteric binding pocket. These findings provide significant structural insights into HS-731 interaction pattern with the opioid receptors that are important for understanding the pharmacology of this peripheral opioid analgesic.
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Affiliation(s)
- Kristina Puls
- Department of Pharmaceutical Chemistry, Institute of Pharmcy, Freie Universität Berlin, Königin-Luise-Str. 2+4, D-14195 Berlin, Germany;
| | - Helmut Schmidhammer
- Department of Pharmaceutical Chemistry, Institute of Pharmacy and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria;
| | - Gerhard Wolber
- Department of Pharmaceutical Chemistry, Institute of Pharmcy, Freie Universität Berlin, Königin-Luise-Str. 2+4, D-14195 Berlin, Germany;
| | - Mariana Spetea
- Department of Pharmaceutical Chemistry, Institute of Pharmacy and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria;
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3
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Chen KYM, Keri D, Barth P. Computational design of G Protein-Coupled Receptor allosteric signal transductions. Nat Chem Biol 2019; 16:77-86. [PMID: 31792443 DOI: 10.1038/s41589-019-0407-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 10/10/2019] [Indexed: 12/17/2022]
Abstract
Membrane receptors sense and transduce extracellular stimuli into intracellular signaling responses but the molecular underpinnings remain poorly understood. We report a computational approach for designing protein allosteric signaling functions. By combining molecular dynamics simulations and design calculations, the method engineers amino-acid 'microswitches' at allosteric sites that modulate receptor stability or long-range coupling, to reprogram specific signaling properties. We designed 36 dopamine D2 receptor variants, whose constitutive and ligand-induced signaling agreed well with our predictions, repurposed the D2 receptor into a serotonin biosensor and predicted the signaling effects of more than 100 known G-protein-coupled receptor (GPCR) mutations. Our results reveal the existence of distinct classes of allosteric microswitches and pathways that define an unforeseen molecular mechanism of regulation and evolution of GPCR signaling. Our approach enables the rational design of allosteric receptors with enhanced stability and function to facilitate structural characterization, and reprogram cellular signaling in synthetic biology and cell engineering applications.
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Affiliation(s)
- Kuang-Yui Michael Chen
- Swiss Federal Institute of Technology (EPFL), Institute of Bioengineering, Lausanne, Switzerland.,Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA.,Department of Cell Biology and Human Anatomy, University of California at Davis, Davis, CA, USA
| | - Daniel Keri
- Swiss Federal Institute of Technology (EPFL), Institute of Bioengineering, Lausanne, Switzerland
| | - Patrick Barth
- Swiss Federal Institute of Technology (EPFL), Institute of Bioengineering, Lausanne, Switzerland. .,Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA. .,Department of Pharmacology, Baylor College of Medicine, Houston, TX, USA. .,Structural and Computational Biology and Molecular Biophysics Graduate Program, Baylor College of Medicine, Houston, TX, USA.
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4
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Gendron L, Cahill CM, von Zastrow M, Schiller PW, Pineyro G. Molecular Pharmacology of δ-Opioid Receptors. Pharmacol Rev 2017; 68:631-700. [PMID: 27343248 DOI: 10.1124/pr.114.008979] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Opioids are among the most effective analgesics available and are the first choice in the treatment of acute severe pain. However, partial efficacy, a tendency to produce tolerance, and a host of ill-tolerated side effects make clinically available opioids less effective in the management of chronic pain syndromes. Given that most therapeutic opioids produce their actions via µ-opioid receptors (MOPrs), other targets are constantly being explored, among which δ-opioid receptors (DOPrs) are being increasingly considered as promising alternatives. This review addresses DOPrs from the perspective of cellular and molecular determinants of their pharmacological diversity. Thus, DOPr ligands are examined in terms of structural and functional variety, DOPrs' capacity to engage a multiplicity of canonical and noncanonical G protein-dependent responses is surveyed, and evidence supporting ligand-specific signaling and regulation is analyzed. Pharmacological DOPr subtypes are examined in light of the ability of DOPr to organize into multimeric arrays and to adopt multiple active conformations as well as differences in ligand kinetics. Current knowledge on DOPr targeting to the membrane is examined as a means of understanding how these receptors are especially active in chronic pain management. Insight into cellular and molecular mechanisms of pharmacological diversity should guide the rational design of more effective, longer-lasting, and better-tolerated opioid analgesics for chronic pain management.
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Affiliation(s)
- Louis Gendron
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
| | - Catherine M Cahill
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
| | - Mark von Zastrow
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
| | - Peter W Schiller
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
| | - Graciela Pineyro
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
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Xiao X, Zeng X, Yuan Y, Gao N, Guo Y, Pu X, Li M. Understanding the conformation transition in the activation pathway of β2 adrenergic receptor via a targeted molecular dynamics simulation. Phys Chem Chem Phys 2015; 17:2512-22. [DOI: 10.1039/c4cp04528a] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The conformation transition in the activation pathway of β2 adrenergic receptor was explored mainly using a target molecular dynamics simulation.
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Affiliation(s)
- Xiuchan Xiao
- Faculty of Chemistry
- Sichuan University
- Chengdu
- People's Republic of China
| | - Xiaojun Zeng
- Faculty of Chemistry
- Sichuan University
- Chengdu
- People's Republic of China
| | - Yuan Yuan
- College of Management
- Southwest University for Nationalities
- Chengdu
- People's Republic of China
| | - Nan Gao
- Faculty of Chemistry
- Sichuan University
- Chengdu
- People's Republic of China
| | - Yanzhi Guo
- Faculty of Chemistry
- Sichuan University
- Chengdu
- People's Republic of China
| | - Xuemei Pu
- Faculty of Chemistry
- Sichuan University
- Chengdu
- People's Republic of China
| | - Menglong Li
- Faculty of Chemistry
- Sichuan University
- Chengdu
- People's Republic of China
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6
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Understanding the effects on constitutive activation and drug binding of a D130N mutation in the β2 adrenergic receptor via molecular dynamics simulation. J Mol Model 2014; 20:2491. [PMID: 25342155 DOI: 10.1007/s00894-014-2491-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Accepted: 10/06/2014] [Indexed: 01/21/2023]
Abstract
G-protein-coupled receptors (GPCRs) are currently one of the largest families of drug targets. The constitutive activation induced by mutation of key GPCR residues is associated closely with various diseases. However, the structural basis underlying such activation and its role in drug binding has remained unclear. Herein, we used all-atom molecular dynamics simulations and free energy calculations to study the effects of a D130N mutation on the structure of β2 adrenergic receptor (β2AR) and its binding of the agonist salbutamol. The results indicate that the mutation caused significant changes in some key helices. In particular, the mutation leads to the departure of transmembrane 3 (TM3) from transmembrane 6 (TM6) and marked changes in the NPxxY region as well as the complete disruption of a key ionic lock, all of which contribute to the observed constitutive activation. In addition, the D130N mutation weakens some important H-bonds, leading to structural changes in these regions. Binding free energy calculations indicate that van der Waals and electrostatic interactions are the main driving forces in binding salbutamol; however, binding strength in the mutant β2AR is significantly enhanced mainly through modifying electrostatic interactions. Further analysis revealed that the increase in binding energy upon mutation stems mainly from the H-bonds formed between the hydroxyl group of salbutamol and the serine residues of TM5. This observation suggests that modifications of the H-bond groups of this drug could significantly influence drug efficacy in the treatment of diseases associated with this mutation.
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Sacharczuk M, Lesniak A, Lipkowski AW, Korostynski M, Przewlocki R, Sadowski B. Association between the A107V substitution in the δ-opioid receptors and ethanol drinking in mice selected for high and low analgesia. Addict Biol 2014; 19:643-51. [PMID: 23301597 DOI: 10.1111/adb.12030] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Experimental evidence suggests that endogenous opioids play an important role in the development of ethanol addiction. In this study, we employed two mouse lines divergently bred for opioid-mediated stress-induced analgesia. In comparison with HA (high analgesia line) mice, LA (low analgesia line) mice, having lower opioid receptor system activity, manifest enhanced basal as well as stress-induced ethanol drinking. Here, we found that recently discovered C320T transition in exon 2 of the δ-opioid receptor gene (EU446125.1), which results in an A107V substitution (ACA23171.1), leads to higher ethanol preference in CT mice compared with CC homozygotes. This genetic association is particularly evident under chronic mild stress (CMS) conditions. The interaction between stress and ethanol intake was significantly stronger in HA than in LA mice. Ethanol almost completely attenuated the pro-depressive effect of CMS (assessed with the tail suspension test) in both the CC and CT genotypes in the HA line. In the LA mice, a lack of response to ethanol was observed in the CC genotype, whereas ethanol consumption strengthened depressive-like behaviours in CT individuals. Our results suggest that constitutively active A107V substitution in δ-opioid receptors may be involved in stress-enhanced vulnerability to ethanol abuse and in the risk of ethanol dependence.
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Affiliation(s)
- Mariusz Sacharczuk
- Department of Molecular Cytogenetics, Institute of Genetics and Animal Breeding, Polish Academy of Sciences, Poland
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8
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Ahn KH, Scott CE, Abrol R, Goddard WA, Kendall DA. Computationally-predicted CB1 cannabinoid receptor mutants show distinct patterns of salt-bridges that correlate with their level of constitutive activity reflected in G protein coupling levels, thermal stability, and ligand binding. Proteins 2013; 81:1304-17. [PMID: 23408552 DOI: 10.1002/prot.24264] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 12/21/2013] [Accepted: 01/21/2013] [Indexed: 11/09/2022]
Abstract
The cannabinoid receptor 1 (CB1), a member of the class A G-protein-coupled receptor (GPCR) family, possesses an observable level of constitutive activity. Its activation mechanism, however, has yet to be elucidated. Previously we discovered dramatic changes in CB1 activity due to single mutations; T3.46A, which made the receptor inactive, and T3.46I and L3.43A, which made it essentially fully constitutively active. Our subsequent prediction of the structures of these mutant receptors indicated that these changes in activity are explained in terms of the pattern of salt-bridges in the receptor region involving transmembrane domains 2, 3, 5, and 6. Here we identified key salt-bridges, R2.37 + D6.30 and D2.63 + K3.28, critical for CB1 inactive and active states, respectively, and generated new mutant receptors that we predicted would change CB1 activity by either precluding or promoting these interactions. We find that breaking the R2.37 + D6.30 salt-bridge resulted in substantial increase in G-protein coupling activity and reduced thermal stability relative to the wild-type reflecting the changes in constitutive activity from inactive to active. In contrast, breaking the D2.63 + K3.28 salt-bridge produced the opposite profile suggesting this interaction is critical for the receptor activation. Thus, we demonstrate an excellent correlation with the predicted pattern of key salt-bridges and experimental levels of activity and conformational flexibility. These results are also consistent with the extended ternary complex model with respect to shifts in agonist and inverse agonist affinity and provide a powerful framework for understanding the molecular basis for the multiple stages of CB1 activation and that of other GPCRs in general.
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Affiliation(s)
- Kwang H Ahn
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, Connecticut 06269-3092, USA
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9
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Kuz'mina NE, Iashkir VA, Merkulov VA, Osipova ES. [The estimation method of compounds opiate activity based on universal three-dimensional model of the nonselective opiate pharmacophore]. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2013; 38:577-90. [PMID: 23342491 DOI: 10.1134/s1068162012050081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Created by means alternative strategy of structural similarity search universal three-dimensional model of the nonselective opiate pharmacophore and the estimation method of agonistic and antagonistic properties of opiate receptors ligands based on its were described. The examples of the present method use are given for opiate activity estimation of compounds essentially distinguished on the structure from opiates and traditional opioids.
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10
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Shenker A. Activating Mutations of the Lutropin Choriogonadotropin Receptor in Precocious Puberty. ACTA ACUST UNITED AC 2011. [DOI: 10.3109/10606820212138] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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De Wachter R, de Graaf C, Keresztes A, Vandormael B, Ballet S, Tóth G, Rognan D, Tourwé D. Synthesis, Biological Evaluation, and Automated Docking of Constrained Analogues of the Opioid Peptide H-Dmt-d-Ala-Phe-Gly-NH2 Using the 4- or 5-Methyl Substituted 4-Amino-1,2,4,5-tetrahydro-2-benzazepin-3-one Scaffold. J Med Chem 2011; 54:6538-47. [DOI: 10.1021/jm2003574] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Rien De Wachter
- Department of Organic Chemistry, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
| | - Chris de Graaf
- Structural Chemogenomics, UMR 7200 CNRS-UdS, Université de Strasbourg, Illkirch F-67401, France
- Leiden/Amsterdam Center for Drug Research, Division of Medicinal Chemistry, Faculty of Science, VU University Amsterdam, Amsterdam, The Netherlands
| | - Atilla Keresztes
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Bart Vandormael
- Department of Organic Chemistry, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
| | - Steven Ballet
- Department of Organic Chemistry, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
| | - Géza Tóth
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Didier Rognan
- Structural Chemogenomics, UMR 7200 CNRS-UdS, Université de Strasbourg, Illkirch F-67401, France
| | - Dirk Tourwé
- Department of Organic Chemistry, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
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12
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Ślusarz MJ. Molecular modeling study of the opioid receptor interactions with series of cyclic deltorphin analogues. J Pept Sci 2011; 17:554-64. [DOI: 10.1002/psc.1371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Revised: 02/18/2011] [Accepted: 02/21/2011] [Indexed: 11/08/2022]
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13
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Histamine signalling in Schistosoma mansoni: Immunolocalisation and characterisation of a new histamine-responsive receptor (SmGPR-2). Int J Parasitol 2010; 40:1395-406. [DOI: 10.1016/j.ijpara.2010.04.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Revised: 04/01/2010] [Accepted: 04/05/2010] [Indexed: 11/24/2022]
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14
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Nikiforovich GV, Baranski TJ. Computational Modeling of Constitutively Active Mutants of GPCRs. Methods Enzymol 2010; 485:369-91. [DOI: 10.1016/b978-0-12-381296-4.00021-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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15
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Structural requirements for ligands of the δ-opioid receptor. JOURNAL OF THE SERBIAN CHEMICAL SOCIETY 2009. [DOI: 10.2298/jsc0911207m] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The ?-opioid receptor is sensitive to ligand geometry. In order to assist the synthesis of new ?-selective opioid ligands, the structure elements of ?-selective opioid ligands necessary for their effective binding were investigated. The automated docking procedure with a flexible ligand was used to simulate the binding of 17 ?-selective ligands to the ?-receptor. It was found that voluminous N-alkyl groups reduce the binding potency of naltrindole derivatives by preventing the ligands from adopting the preferred conformation in the receptor. This was confirmed by enantiospecific binding of chiral compounds where only one enantiomer adopts the naltrindole-like preferred conformation in the binding pocket. Voluminous groups replacing the hydroxyl group in the 3-hydroxybenzyl fragment of naltrindole analogs reduce the binding potency due to unfavorable steric interactions with the receptor. The two diastereoisomers of the potent ?-opioid ligand SNC80 confirmed the preferred binding conformation and the major receptor-ligand interactions.
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16
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Docking studies suggest ligand-specific delta-opioid receptor conformations. J Mol Model 2008; 15:267-80. [PMID: 19052783 DOI: 10.1007/s00894-008-0396-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2008] [Accepted: 11/03/2008] [Indexed: 10/21/2022]
Abstract
An automated docking procedure was used to study binding of a series of delta-selective ligands to three models of the delta-opioid receptor. These models are thought to represent the three ligand-specific receptor conformations. Docking results are in agreement with point mutation studies and suggest that different ligands--agonists and antagonists--may bind to the same binding site under different receptor conformations. Docking to different receptor models (conformations) also suggests that by changing to a receptor-specific conformation, the receptor may open or close different binding sites to other ligands.
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17
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Conformationally constrained opioid ligands: the Dmt-Aba and Dmt-Aia versus Dmt-Tic scaffold. Bioorg Med Chem Lett 2008; 19:433-7. [PMID: 19062273 DOI: 10.1016/j.bmcl.2008.11.051] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Revised: 11/13/2008] [Accepted: 11/14/2008] [Indexed: 11/23/2022]
Abstract
Replacement of the constrained phenylalanine analogue 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (Tic) in the opioid Dmt-Tic-Gly-NH-Bn scaffold by the 4-amino-1,2,4,5-tetrahydro-indolo[2,3-c]azepin-3-one (Aia) and 4-amino-1,2,4,5-tetrahydro-2-benzazepin-3-one (Aba) scaffolds has led to the discovery of novel potent mu-selective agonists (Structures 5 and 12) as well as potent and selective delta-opioid receptor antagonists (Structures 9 and 15). Both stereochemistry and N-terminal N,N-dimethylation proved to be crucial factors for opioid receptor selectivity and functional bioactivity in the investigated small peptidomimetic templates. In addition to the in vitro pharmacological evaluation, automated docking models of Dmt-Tic and Dmt-Aba analogues were constructed in order to rationalize the observed structure-activity data.
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Hossain M, Ahmed M, Bhuiyan MA, Ishiguro M, Nakamura T, Ozaki M, Nagatomo T. Mutation of important amino acid residue of Asp104Lys in human beta(1)-adrenergic receptor triggers functional and constitutive inactivation. Biol Pharm Bull 2008; 31:1517-22. [PMID: 18670082 DOI: 10.1248/bpb.31.1517] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Based on our previous molecular modeling and radioligand binding study, we have demonstrated that aspartic acid of 104 in transmembrane helix (TMH) II of beta(1)-adrenergic receptor (beta(1)-AR) is important for functional characteristics of these receptors. We have also showed that mutation of negatively charged aspartic acid to neutral charged alanine exhibited constitutive activity of beta(1)-AR. However, the mutation of negatively charged aspartic acid to positively charged lysine is still remained to be examined, which is very important to know for fully understanding the characteristics of beta(1)-AR. At the present study, we mutated aspartic acid to lysine (Asp104Lys) residue in human beta(1)-AR. This resultant mutant (Asp104Lys) markedly reduced the binding affinity of isoproterenol and (-)-epinephrine. On the other hand, antagonist binding with this mutant was similar to the wild type receptor. Isoproterenol at its saturation concentrations produced lower amount of intracellular cyclic adenosine-3',5' cyclic monophosphate (cAMP) in HEK-293 cells expressing Asp104Lys mutant receptor as compared to cells expressing wild type receptor. Moreover, cAMP accumulation of Asp104Lys mutant was unchanged in the presence or absence of isoproterenol. Therefore, it has been demonstrated that Asp104Lys mutation in the human beta(1)-AR differentially affects the binding of antagonist and exhibits a functional uncoupling of G-protein-coupled receptors. Thus, we may suggest that mutation of negatively charged aspartic acid to positively charged lysine as well as neutral charged alanine may help to understand the mechanism of the activation or inactivation of beta(1)-AR by its conformational changes and this finding would be helpful for clarifying the functional responses mediated by beta(1)-AR.
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Affiliation(s)
- Murad Hossain
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, Niigata, Japan
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19
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Standfuss J, Zaitseva E, Mahalingam M, Vogel R. Structural impact of the E113Q counterion mutation on the activation and deactivation pathways of the G protein-coupled receptor rhodopsin. J Mol Biol 2008; 380:145-57. [PMID: 18511075 PMCID: PMC2726285 DOI: 10.1016/j.jmb.2008.04.055] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Revised: 03/12/2008] [Accepted: 04/21/2008] [Indexed: 11/16/2022]
Abstract
Disruption of an interhelical salt bridge between the retinal protonated Schiff base linked to H7 and Glu113 on H3 is one of the decisive steps during activation of rhodopsin. Using previously established stabilization strategies, we engineered a stabilized E113Q counterion mutant that converted rhodopsin to a UV-absorbing photoreceptor with deprotonated Schiff base and allowed reconstitution into native-like lipid membranes. Fourier-transform infrared difference spectroscopy reveals a deprotonated Schiff base in the photoproducts of the mutant up to the active state Meta II, the absence of the classical pH-dependent Meta I/Meta II conformational equilibrium in favor of Meta II, and an anticipation of active state features under conditions that stabilize inactive photoproduct states in wildtype rhodopsin. Glu181 on extracellular loop 2, is found to be unable to maintain a counterion function to the Schiff base on the activation pathway of rhodopsin in the absence of the primary counterion, Glu113. The Schiff base becomes protonated in the transition to Meta III. This protonation is, however, not associated with a deactivation of the receptor, in contrast to wildtype rhodopsin. Glu181 is suggested to be the counterion in the Meta III state of the mutant and appears to be capable of stabilizing a protonated Schiff base in Meta III, but not of constraining the receptor in an inactive conformation.
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Affiliation(s)
- Jörg Standfuss
- Structural Studies Division, MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
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20
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Eglen RM, Bosse R, Reisine T. Emerging concepts of guanine nucleotide-binding protein-coupled receptor (GPCR) function and implications for high throughput screening. Assay Drug Dev Technol 2007; 5:425-51. [PMID: 17638542 DOI: 10.1089/adt.2007.062] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Guanine nucleotide binding protein (G protein) coupled receptors (GPCRs) comprise one of the largest families of proteins in the human genome and are a target for 40% of all approved drugs. GPCRs have unique structural motifs that allow them to interact with a wide and diverse series of extracellular ligands, as well as intracellular proteins, G proteins, receptor activity-modifying proteins, arrestins, and indeed other receptors. This distinctive structure has led to numerous efforts to discover drugs against GPCRs with targeted therapeutic uses. Such "designer" drugs currently include allosteric regulators, inverse agonists, and drugs targeting hetero-oligomeric complexes. Moreover, the large family of orphan GPCRs provides a rich and novel field of targets to discover drugs with unique therapeutic properties. The numerous technologies to discover GPCR drugs have also greatly advanced over the years, facilitating compound screening against known and orphan GPCRs, as well as in the identification of unique designer GPCR drugs. Indeed, high throughput screening (HTS) technologies employing functional cell-based approaches are now widely used. These include measurement of second messenger accumulation such as cyclic AMP, calcium ions, and inositol phosphates, as well as mitogen-activated protein kinase activation, protein-protein interactions, and GPCR oligomerization. This review focuses on how the improved understanding of the molecular pharmacology of GPCRs, coupled with a plethora of novel HTS technologies, is leading to the discovery and development of an entirely new generation of GPCR-based therapeutics.
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Affiliation(s)
- Richard M Eglen
- Discovery and Research Reagents, PerkinElmer Life and Analytical Sciences, Waltham, MA 02451, USA.
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21
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Cavalli A, Carloni P, Recanatini M. Target-Related Applications of First Principles Quantum Chemical Methods in Drug Design. Chem Rev 2006; 106:3497-519. [PMID: 16967914 DOI: 10.1021/cr050579p] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Andrea Cavalli
- Department of Pharmaceutical Sciences, University of Bologna, Via Belmeloro 6, I-40126 Bologna, Italy
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22
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Kong MMC, Fan T, Varghese G, O'dowd BF, George SR. Agonist-induced cell surface trafficking of an intracellularly sequestered D1 dopamine receptor homo-oligomer. Mol Pharmacol 2006; 70:78-89. [PMID: 16597839 DOI: 10.1124/mol.105.021246] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The role of oligomerization in D1 dopamine receptor trafficking to the cell surface was examined using conformationally distinct variants of this receptor. Substitution of the highly conserved aspartic acid (Asp103) in transmembrane domain 3 resulted in a constitutively active receptor, D103A, that did not bind agonists or antagonists but trafficked to the cell surface as oligomers. Coexpression of D103A with the wild-type D1 receptor in human embryonic kidney 293t cells resulted in inhibition of cell surface expression of the D1 receptor because of receptor oligomerization, causing intracellular retention of both proteins. Rescue of the intracellularly retained oligomer could be achieved only by membrane-permeable full and partial agonists, which resulted in cell surface expression of the D1 receptor, whereas cell-permeable antagonists and cell impermeable agonists had no effect. Cell surface fluorescence resonance energy transfer studies of cells coexpressing D103A and D1 revealed no signal before agonist treatment but a robust signal after agonist treatment, indicating that the intact D1/D103A oligomer reached the cell surface only after agonist treatment but not under basal conditions. This suggests that rescue of the retained D1/D103A oligomer to the cell surface was a result of an agonist-induced change in the conformation of D1, permitting cell surface trafficking of the D1/D103A receptor oligomeric complex from the endoplasmic reticulum.
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Affiliation(s)
- Michael M C Kong
- Department of Pharmacology, University of Toronto; Medical Sciences Building Rm 4358, Toronto, ON, Canada M5S 1A8
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23
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Xu W, Campillo M, Pardo L, de Riel JK, Liu-Chen LY. The seventh transmembrane domains of the delta and kappa opioid receptors have different accessibility patterns and interhelical interactions. Biochemistry 2006; 44:16014-25. [PMID: 16331961 PMCID: PMC2688720 DOI: 10.1021/bi050938a] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We applied the substituted cysteine accessibility method (SCAM) to map the residues of the transmembrane helices (TMs) 7 of delta and kappa opioid receptors (deltaOR and kappaOR) that are on the water-accessible surface of the binding-site crevices. A total of 25 consecutive residues (except C7.38) in the TMs 7 were mutated to Cys, one at a time, and each mutant was expressed in HEK 293 cells. Most mutants displayed similar binding affinity for [(3)H]diprenorphine, an antagonist, as the wild types. Pretreatment with (2-aminoethyl)methanethiosulfonate (MTSEA) inhibited [(3)H]diprenorphine binding to eight deltaOR and eight kappaOR mutants. All mutants except deltaOR L7.52(317)C were protected by naloxone from the MTSEA effect, indicating that the side chains of V7.31(296), A7.34(299), I7.39(304), L7.41(306), G7.42(307), P7.50(315), and Y7.53(318) of deltaOR and S7.34(311), F7.37(314), I7.39(316), A7.40(317), L7.41(318), G7.42(319), Y7.43(320), and N7.49(326) of kappaOR are on the water-accessible surface of the binding pockets. Combining the SCAM data with rhodopsin-based molecular models of the receptors led to the following conclusions. (i) The residues of the extracellular portion of TM7 predicted to face TM1 are sensitive to MTSEA in kappaOR but are not in deltaOR. Thus, TM1 may be closer to TM7 in deltaOR than in kappaOR. (ii) MTSEA-sensitive mutants start at position 7.31(296) in deltaOR and at 7.34(311) in kappaOR, suggesting that TM7 in deltaOR may have an additional helical turn (from 7.30 to 7.33). (iii) There is a conserved hydrogen-bond network linking D2.50 of the NLxxxD motif in TM2 with W6.48 of the CWxP motif in TM6. (iv) The NPxxY motif in TM7 interacts with TM2, TM6, and helix 8 to maintain receptors in inactive states. To the best of our knowledge, this represents the first such comparison of the structures of two highly homologous GPCRs.
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MESH Headings
- Amino Acid Sequence
- Animals
- Binding Sites
- Cattle
- Cell Line
- Cysteine/metabolism
- Humans
- Hydrogen Bonding
- Models, Molecular
- Molecular Sequence Data
- Protein Structure, Secondary
- Receptors, Opioid, delta/chemistry
- Receptors, Opioid, delta/genetics
- Receptors, Opioid, kappa/chemistry
- Receptors, Opioid, kappa/genetics
- Sequence Alignment
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Affiliation(s)
- Wei Xu
- Department of Pharmacology and Center for Substance Abuse Research, Temple University School of Medicine, Philadelphia, PA
| | - Mercedes Campillo
- Laboratori de Medicina Computacional, Unitat de Bioestadística and Institut de Neurociències, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain
| | - Leonardo Pardo
- Laboratori de Medicina Computacional, Unitat de Bioestadística and Institut de Neurociències, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain
| | - J. Kim de Riel
- Fels Institute for Molecular Biology and Cancer Research, Temple University School of Medicine, Philadelphia, PA
| | - Lee-Yuan Liu-Chen
- Department of Pharmacology and Center for Substance Abuse Research, Temple University School of Medicine, Philadelphia, PA
- Address correspondence to: Dr. Lee-Yuan Liu-Chen, Department of Pharmacology, Temple University School of Medicine, 3420 N. Broad St., Philadelphia, PA 19140, phone: (215) 707−4188; fax: (215) 707−7068; e-mail:
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24
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Pogozheva ID, Przydzial MJ, Mosberg HI. Homology modeling of opioid receptor-ligand complexes using experimental constraints. AAPS JOURNAL 2005; 7:E434-48. [PMID: 16353922 PMCID: PMC2750980 DOI: 10.1208/aapsj070243] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Opioid receptors interact with a variety of ligands, including endogenous peptides, opiates, and thousands of synthetic compounds with different structural scaffolds. In the absence of experimental structures of opioid receptors, theoretical modeling remains an important tool for structure-function analysis. The combination of experimental studies and modeling approaches allows development of realistic models of ligand-receptor complexes helpful for elucidation of the molecular determinants of ligand affinity and selectivity and for understanding mechanisms of functional agonism or antagonism. In this review we provide a brief critical assessment of the status of such theoretical modeling and describe some common problems and their possible solutions. Currently, there are no reliable theoretical methods to generate the models in a completely automatic fashion. Models of higher accuracy can be produced if homology modeling, based on the rhodopsin X-ray template, is supplemented by experimental structural constraints appropriate for the active or inactive receptor conformations, together with receptor-specific and ligand-specific interactions. The experimental constraints can be derived from mutagenesis and cross-linking studies, correlative replacements of ligand and receptor groups, and incorporation of metal binding sites between residues of receptors or receptors and ligands. This review focuses on the analysis of similarity and differences of the refined homology models of mu, delta, and kappa-opioid receptors in active and inactive states, emphasizing the molecular details of interaction of the receptors with some representative peptide and nonpeptide ligands, underlying the multiple modes of binding of small opiates, and the differences in binding modes of agonists and antagonists, and of peptides and alkaloids.
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Affiliation(s)
- Irina D Pogozheva
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109, USA
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25
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Bywater RP. Location and nature of the residues important for ligand recognition in G-protein coupled receptors. J Mol Recognit 2005; 18:60-72. [PMID: 15386622 DOI: 10.1002/jmr.685] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The overall structure of the biogenic amine subclass of the G-protein-coupled receptors, and of their ligand binding sites, is discussed with the aim of highlighting the major structural features of these receptors that are responsible for ligand recognition. A comparison is made between biogenic amine receptors, peptide receptors of the rhodopsin class, and the secretin receptors which all have peptide ligands. The question of where the peptide ligands bind, whether at extracellular sites or within the transmembrane helix bundle, is discussed. The suitability of the rhodopsin crystal structure as a template for construction of homology models is discussed and it is concluded that there are many reasons why a caution should be issued against using it uncritically.
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Affiliation(s)
- Robert P Bywater
- Adelard Institute, London, UK and Division of Molecular Neurobiology, Wallenberg Neuroscience Center, Lund University, Lund, Sweden.
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26
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Browning A. Recent developments in the discovery of melanin-concentrating hormone antagonists: novel antiobesity agents. Expert Opin Ther Pat 2005. [DOI: 10.1517/13543776.14.3.313] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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27
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Tryoen-Tóth P, Décaillot FM, Filliol D, Befort K, Lazarus LH, Schiller PW, Schmidhammer H, Kieffer BL. Inverse agonism and neutral antagonism at wild-type and constitutively active mutant delta opioid receptors. J Pharmacol Exp Ther 2004; 313:410-21. [PMID: 15590769 DOI: 10.1124/jpet.104.077321] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The delta opioid receptor modulates nociceptive and emotional behaviors. This receptor has been shown to exhibit measurable spontaneous activity. Progress in understanding the biological relevance of this activity has been slow, partly due to limited characterization of compounds with intrinsic negative activity. Here, we have used constitutively active mutant (CAM) delta receptors in two different functional assays, guanosine 5'-O-(3-thio)triphosphate binding and a reporter gene assay, to test potential inverse agonism of 15 delta opioid compounds, originally described as antagonists. These include the classical antagonists naloxone, naltrindole, 7-benzylidene-naltrexone, and naltriben, a new set of naltrindole derivatives, H-Tyr-Tic-Phe-Phe-OH (TIPP) and H-Tyr-TicPsi[CH2N]Cha-Phe-OH [TICP(Psi)], as well as three 2',6'-dimethyltyrosine-1,2,3,4-tetrahydroquinoline-3-carboxylate (Dmt-Tic) peptides. A reference agonist, SNC 80 [(+)-4-[(alphaR)-alpha-((2S,5R)-4-Allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl]-N,N-diethylbenzamide], and inverse agonist, ICI 174864 (N,N-diallyl-Tyr-Aib-Aib-Phe-Leu), were also included. In a screen using wild-type and CAM M262T delta receptors, naltrindole (NTI) and close derivatives were mostly inactive, and TIPP behaved as an agonist, whereas Dmt-Tic-OH and N,N(CH3)2-Dmt-Tic-NH2 showed inverse agonism. The two latter compounds showed negative activity across 27 CAM receptors, suggesting that this activity was independent from the activation mechanism. These two compounds also exhibited nanomolar potencies in dose-response experiments performed on wild-type, M262T, Y308H, and C328R CAM receptors. TICP(Psi) exhibited strong inverse agonism at the Y308H receptor. We conclude that the stable N,N(CH3)2-Dmt-Tic-NH2 compound represents a useful tool to explore the spontaneous activity of delta receptors, and NTI and novel derivatives behave as neutral antagonists.
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Affiliation(s)
- P Tryoen-Tóth
- Institut de Génétique et Biologie Moléculaire et Cellulaire, 1 rue Laurent Fries, B.P. 1042, 67404 Illkirch Cedex, France
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28
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Kristiansen K. Molecular mechanisms of ligand binding, signaling, and regulation within the superfamily of G-protein-coupled receptors: molecular modeling and mutagenesis approaches to receptor structure and function. Pharmacol Ther 2004; 103:21-80. [PMID: 15251227 DOI: 10.1016/j.pharmthera.2004.05.002] [Citation(s) in RCA: 394] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The superfamily of G-protein-coupled receptors (GPCRs) could be subclassified into 7 families (A, B, large N-terminal family B-7 transmembrane helix, C, Frizzled/Smoothened, taste 2, and vomeronasal 1 receptors) among mammalian species. Cloning and functional studies of GPCRs have revealed that the superfamily of GPCRs comprises receptors for chemically diverse native ligands including (1) endogenous compounds like amines, peptides, and Wnt proteins (i.e., secreted proteins activating Frizzled receptors); (2) endogenous cell surface adhesion molecules; and (3) photons and exogenous compounds like odorants. The combined use of site-directed mutagenesis and molecular modeling approaches have provided detailed insight into molecular mechanisms of ligand binding, receptor folding, receptor activation, G-protein coupling, and regulation of GPCRs. The vast majority of family A, B, C, vomeronasal 1, and taste 2 receptors are able to transduce signals into cells through G-protein coupling. However, G-protein-independent signaling mechanisms have also been reported for many GPCRs. Specific interaction motifs in the intracellular parts of these receptors allow them to interact with scaffold proteins. Protein engineering techniques have provided information on molecular mechanisms of GPCR-accessory protein, GPCR-GPCR, and GPCR-scaffold protein interactions. Site-directed mutagenesis and molecular dynamics simulations have revealed that the inactive state conformations are stabilized by specific interhelical and intrahelical salt bridge interactions and hydrophobic-type interactions. Constitutively activating mutations or agonist binding disrupts such constraining interactions leading to receptor conformations that associates with and activate G-proteins.
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Affiliation(s)
- Kurt Kristiansen
- Department of Pharmacology, Institute of Medical Biology, University of Tromsø, N-9037 Tromsø, Norway.
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29
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Rezmann-Vitti LA, Louis SNS, Nero TL, Jackman GP, Iakovidis D, Machida CA, Louis WJ. Agonist binding and activation of the rat beta(1)-adrenergic receptor: role of Trp(134(3.28)), Ser(190(4.57)) and Tyr(356(7.43)). Biochem Pharmacol 2004; 68:675-88. [PMID: 15276075 DOI: 10.1016/j.bcp.2004.04.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2004] [Accepted: 04/27/2004] [Indexed: 11/21/2022]
Abstract
We investigated the role of Trp(134(3.28)), Ser(190(4.57)) and Tyr(356(7.43)) in agonist binding to, and activation of, the rat beta(1)-adrenergic receptor by comparing pK(i)s and functional responses of W134A, S190A and Y356F mutant receptors to wild type, all stably expressed in CHO cells. All three mutations significantly (P < 0.05) reduced adenylyl cyclase intrinsic activity (IA) compared to wild type in response to stimulation with both (-)-isoprenaline (53-88%) and (-)-RO363 (46-61%), and there was no significant correlation either between IA or pD(2) and pK(i) (P > 0.4), suggesting that changes in pK(i) were not sufficient to explain the fall in adenylyl cyclase activity. The most pronounced reduction in affinity (126-fold, P < 0.01) was displayed by xamoterol for the Y356F mutation, suggesting that xamoterol is able to directly interact with Tyr(356(7.43)). For the other agonists, the change in pK(i) values for the mutant receptors ranged from a 20-fold decrease to a 2-fold increase compared to the wild type. In a three-dimensional model of the rat beta(1)-adrenergic receptor, Trp(134(3.28)) and Tyr(356(7.43)) form part of a hydrophobic binding pocket involving residues in transmembrane helices 1, 2, 3 and 7. Our results suggest that Trp(134(3.28)) and Tyr(356(7.43)), together with Trp(353(7.40)), are able to interact via pi-pi interactions to stabilize the extracellular ends of transmembrane helices 3 and 7. Ser(190(4.57)) appears to be involved in a hydrogen bonding network, which maintains the spatial relationship between transmembrane helices 3 and 4. These interhelical interactions suggest that the three mutated residues stabilize the active receptor state by maintaining the proper packing of their respective transmembrane helix within the helix bundle, facilitating the appropriate movement and rotation of the transmembrane regions during the activation process.
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Affiliation(s)
- Linda A Rezmann-Vitti
- Department of Medicine, Clinical Pharmacology and Therapeutics Unit, The University of Melbourne, Austin Health, Heidelberg 3084, Vic., Australia
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30
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McAllister SD, Hurst DP, Barnett-Norris J, Lynch D, Reggio PH, Abood ME. Structural mimicry in class A G protein-coupled receptor rotamer toggle switches: the importance of the F3.36(201)/W6.48(357) interaction in cannabinoid CB1 receptor activation. J Biol Chem 2004; 279:48024-37. [PMID: 15326174 DOI: 10.1074/jbc.m406648200] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In this study, we tested the hypothesis that a CB(1) TMH3-4-5-6 aromatic microdomain, which includes F3.25(190), F3.36(201), W5.43(280), and W6.48(357), is centrally involved in CB(1) receptor activation, with the F3.36(201)/W6.48(357) interaction key to the maintenance of the CB(1)-inactive state. We have shown previously that when F3.36(201), W5.43(280), and W6.48(357) are individually mutated to alanine, a significant reduction in ligand binding affinity is observed in the presence of WIN 55,212-2 and SR141716A but not CP55,940 and anandamide. In the work presented here, we report a detailed functional analysis of the F3.36(201)A, F3.25(190)A, W5.43(280)A, and W6.48(357)A mutant receptors in stable cell lines created in HEK cells for agonist-stimulated guanosine 5'-3-O-(thio)triphosphate (GTPgammaS) binding and GIRK1/4 channel current effects in Xenopus oocytes where the mutant proteins were expressed transiently. The F3.36(201)A mutation showed statistically significant increases in ligand-independent stimulation of GTPgammaS binding versus wild type CB(1), although basal levels for the W6.48(357)A mutant were not statistically different from wild type CB(1). F3.36(201)A demonstrated a limited activation profile in the presence of multiple agonists. In contrast, enhanced agonist activation was produced by W6.48(357)A. These results suggest that a F3.36(201)/W6.48(357)-specific contact is an important constraint for the CB(1)-inactive state that may need to break during activation. Modeling studies suggest that the F3.36(201)/W6.48(357) contact can exist in the inactive state of CB(1) and be broken in the activated state via a chi(1) rotamer switch (F3.36(201) trans, W6.48(357) g+) --> (F3.36(201) g+, W6.48(357) trans). The F3.36(201)/W6.48(357) interaction therefore may represent a "toggle switch" for activation of CB(1).
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Affiliation(s)
- Sean D McAllister
- California Pacific Medical Center Research Institute, San Francisco, California 94115, USA
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31
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Abstract
A model for the human delta opioid receptor has been generated via sequence alignment, structure building using the crystal structure of bovine rhodopsin as a template, and refinement by molecular dynamics simulation. The model building suggested that, in addition to the previously postulated interaction between D128 and Y308, an internal salt bridge also exists between residues D128 and R192, both of which are conserved in all the opioid receptors. The model and salt bridge were then shown to be stable during a 20-nsec simulation in a lipid bilayer. It is therefore proposed that both of these interactions play a role in stabilizing the inactive state of the receptor. The model is also used in an effort to rationalize many of the mutational studies performed on delta opioid receptors, and to suggest a plausible explanation for the differences between known delta opioid agonists and antagonists.
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Affiliation(s)
- Mahalaxmi Aburi
- Department of Biochemistry, Kansas State University, Manhattan, Kansas 66506-3701, USA
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32
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Brillet K, Kieffer BL, Massotte D. Enhanced spontaneous activity of the mu opioid receptor by cysteine mutations: characterization of a tool for inverse agonist screening. BMC Pharmacol 2003; 3:14. [PMID: 14641935 PMCID: PMC317294 DOI: 10.1186/1471-2210-3-14] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2003] [Accepted: 12/01/2003] [Indexed: 11/10/2022] Open
Abstract
Background The concept of spontaneous- or constitutive-activity has become widely accepted and verified for numerous G protein-coupled receptors and this ligand-independent activity is also acknowledged to play a role in some pathologies. Constitutive activity has been reported for the mu opioid receptor. In some cases the increase in receptor basal activity was induced by chronic morphine administration suggesting that constitutive activity may contribute to the development of drug tolerance and dependence. Constitutively active mutants represent excellent tools for gathering information about the mechanisms of receptor activation and the possible physiological relevance of spontaneous receptor activity. The high basal level of activity of these mutants also allows for easier identification of inverse agonists, defined as ligands able to suppress spontaneous receptor activity, and leads to a better comprehension of their modulatory effects as well as possible in vivo use. Results Cysteines 348 and 353 of the human mu opioid receptor (hMOR) were mutated into alanines and Ala348,353 hMOR was stably expressed in HEK 293 cells. [35S] GTPγS binding experiments revealed that Ala348,353 hMOR basal activity was significantly higher when compared to hMOR, suggesting that the mutant receptor is constitutively active. [35S] GTPγS binding was decreased by cyprodime or CTOP indicating that both ligands have inverse agonist properties. All tested agonists exhibited binding affinities higher for Ala348,353 hMOR than for hMOR, with the exception of endogenous opioid peptides. Antagonist affinity remained virtually unchanged except for CTOP and cyprodime that bound the double mutant with higher affinities. The agonists DAMGO and morphine showed enhanced potency for the Ala348,353 hMOR receptor in [35S] GTPγS experiments. Finally, pretreatment with the antagonists naloxone, cyprodime or CTOP significantly increased Ala348,353 hMOR expression. Conclusion Taken together our data indicate that the double C348/353A mutation results in a constitutively active conformation of hMOR that is still activated by agonists. This is the first report of a stable CAM of hMOR with the potential to screen for inverse agonists.
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Affiliation(s)
- Karl Brillet
- Département des Récepteurs et Protéines Membranaires, UPR 9050, Ecole Supérieure de Biotechnologie de Strasbourg, F-67400 Illkirch-Graffenstaden, France
| | - Brigitte L Kieffer
- Département des Récepteurs et Protéines Membranaires, UPR 9050, Ecole Supérieure de Biotechnologie de Strasbourg, F-67400 Illkirch-Graffenstaden, France
- IGBMC, UMR 7104, F-67404 Illkirch-Graffenstaden cedex, France
| | - Dominique Massotte
- Département des Récepteurs et Protéines Membranaires, UPR 9050, Ecole Supérieure de Biotechnologie de Strasbourg, F-67400 Illkirch-Graffenstaden, France
- IGBMC, UMR 7104, F-67404 Illkirch-Graffenstaden cedex, France
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33
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Décaillot FM, Befort K, Filliol D, Yue S, Walker P, Kieffer BL. Opioid receptor random mutagenesis reveals a mechanism for G protein-coupled receptor activation. Nat Struct Mol Biol 2003; 10:629-36. [PMID: 12847517 DOI: 10.1038/nsb950] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2002] [Accepted: 05/27/2003] [Indexed: 02/06/2023]
Abstract
The high resolution structure of rhodopsin has greatly enhanced current understanding of G protein-coupled receptor (GPCR) structure in the off-state, but the activation process remains to be clarified. We investigated molecular mechanisms of delta-opioid receptor activation without a preconceived structural hypothesis. Using random mutagenesis of the entire receptor, we identified 30 activating point mutations. Three-dimensional modeling revealed an activation path originating from the third extracellular loop and propagating through tightly packed helices III, VI and VII down to a VI-VII cytoplasmic switch. N- and C-terminal determinants also influence receptor activity. Findings for this therapeutically important receptor may apply to other GPCRs that respond to diffusible ligands.
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MESH Headings
- Binding Sites
- Cell Line
- Humans
- In Vitro Techniques
- Models, Molecular
- Mutagenesis
- Point Mutation
- Protein Structure, Tertiary
- Receptors, G-Protein-Coupled/chemistry
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Receptors, Opioid, delta/chemistry
- Receptors, Opioid, delta/genetics
- Receptors, Opioid, delta/metabolism
- Recombinant Proteins/chemistry
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
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Affiliation(s)
- Fabien M Décaillot
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France
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34
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Bissantz C. Conformational Changes of G Protein‐Coupled Receptors During Their Activation by Agonist Binding. J Recept Signal Transduct Res 2003; 23:123-53. [PMID: 14626443 DOI: 10.1081/rrs-120025192] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The superfamily of G protein-coupled receptors (GPCRs) is the largest and most diverse group of transmembrane proteins involved in signal transduction. Many of the over 1000 human GPCRs represent important pharmaceutical targets. However, despite high interest in this receptor family, no high-resolution structure of a human GPCR has been resolved yet. This is mainly due to difficulties in obtaining large quantities of pure and active protein. Until now, only a high-resolution x-ray structure of an inactive state of bovine rhodopsin is available. Since no structure of an active state has been solved, information of the GPCR activation process can be gained only by biophysical techniques. In this review, we first describe what is known about the ground state of GPCRs to then address questions about the nature of the conformational changes taking place during receptor activation and the mechanism controlling the transition from the resting to the active state. Finally, we will also address the question to what extent information about the three-dimensional GPCR structure can be included into pharmaceutical drug design programs.
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Affiliation(s)
- Caterina Bissantz
- Molecular Structure and Design, Pharmaceuticals Division, F. Hoffmann-La Roche Ltd., Basel, Switzerland.
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35
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Abstract
An approach to discover sequence patterns characteristic of ligand classes is described and applied to aminergic G protein-coupled receptors (GPCRs). Putative ligand-binding residue positions were inferred from considering three lines of evidence: conservation in the subfamily absent or underrepresented in the superfamily, any available mutation data, and the physicochemical properties of the ligand. For aminergic GPCRs, the motif is composed of a conserved aspartic acid in the third transmembrane (TM) domain (rhodopsin position 117) and a conserved tryptophan in the seventh TM domain (rhodopsin position 293); the roles of each are readily justified by molecular modeling of ligand-receptor interactions. This minimally defined motif is an appropriate computational tool for identifying additional, potentially novel aminergic GPCRs from a set of experimentally uncharacterized "orphan" GPCRs, complementing existing sequence matching, clustering, and machine-learning techniques. Motif sensitivity stems from the stepwise addition of residues characteristic of an entire class of ligand (and not tailored for any particular biogenic amine). This sensitivity is balanced by careful consideration of residues (evidence drawn from mutation data, correlation of ligand properties to residue properties, and location with respect to the extracellular face), thereby maintaining specificity for the aminergic class. A number of orphan GPCRs assigned to the aminergic class by this motif were later discovered to be a novel subfamily of trace amine GPCRs, as well as the successful classification of the histamine H4 receptor.
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Affiliation(s)
- Enoch S Huang
- Pfizer Discovery Technology Center, 620 Memorial Drive, Cambridge, MA 02139, USA.
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36
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Chaipatikul V, Loh HH, Law PY. Ligand-selective activation of mu-oid receptor: demonstrated with deletion and single amino acid mutations of third intracellular loop domain. J Pharmacol Exp Ther 2003; 305:909-18. [PMID: 12626655 DOI: 10.1124/jpet.102.046219] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The mechanism for the differential regulation of the mu-opioid receptor by agonists is investigated by identifying the receptor domains used to define the relative efficacies of three mu-opioid receptor-selective agonists: [D-Ala2,N-Me-Phe4,Gly5-ol]-enkephalin (DAMGO), morphine, and [N-MePhe3,D-Pro4]-morphiceptin (PL017) to inhibit forskolin-stimulated intracellular cAMP production in human embryonic kidney 293 cells. This was accomplished by systematically deleting four to five amino acids clusters within the third intracellular loop of rat mu-opioid receptor, Arg258 to Arg280, followed by Ala substitution and scanning studies of the 276RRITR280 sequence, the putative G protein-coupling motif. Deletion of the four to five amino acid clusters resulted in differential effects on the affinities of the agonists and antagonists, and also on the potencies and coupling efficiencies of the three opioid agonists. Ala scanning studies of the 276RRITR280 sequence revealed also the differences between [D-Ala2,N-Me-Phe4,Gly5-ol]-enkephalin (DAMGO), morphine, and PL017. Substitution of Arg276 or Ile278 with Ala reduced the potency of DAMGO but not that of morphine PL017. Meanwhile, mutation of Thr279 to Ala increased the potencies of morphine and PL017 but not that of DAMGO. The I278A mutation decreased the DAMGO coupling efficiency but increased the PL017 coupling efficiency. The R280A mutation resulted in the increase in PL017 potency and coupling efficiency without altering those of DAMGO and morphine. Thus, these mutation studies suggested that the activation of mu-opioid receptor and interaction between the critical domains such as RRITR within third intracellular loop and the G proteins are agonist-selective.
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MESH Headings
- Adenylyl Cyclases/metabolism
- Alanine/metabolism
- Analgesics, Opioid/pharmacology
- Cells, Cultured
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Enkephalins/pharmacology
- Gene Deletion
- Humans
- Membrane Proteins/chemistry
- Membrane Proteins/drug effects
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Morphine/pharmacology
- Narcotic Antagonists/pharmacology
- Pertussis Toxin/pharmacology
- Protein Structure, Tertiary
- Receptors, Opioid, mu/chemistry
- Receptors, Opioid, mu/drug effects
- Receptors, Opioid, mu/genetics
- Receptors, Opioid, mu/metabolism
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Affiliation(s)
- Vipa Chaipatikul
- Department of Pharmacology, Medical School, University of Minnesota, Minneapolis, MN 55455-0217, USA
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37
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Kam KWL, New DC, Wong YH. Constitutive activation of the opioid receptor-like (ORL1) receptor by mutation of Asn133 to tryptophan in the third transmembrane region. J Neurochem 2002; 83:1461-70. [PMID: 12472900 DOI: 10.1046/j.1471-4159.2002.01231.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have introduced a series of point mutations into the human opioid receptor-like (ORL1) receptor and characterized them for their ability to constitutively activate G protein-coupled receptor signalling pathways. Among the 12 mutants generated, mutation at Asn133 (N133W) gave increased basal signalling through three separate pathways. N133W increased the basal activity of G14- and G16-dependent pathways by two- to three-fold. The constitutive activity of the mutant was confirmed by the finding that the enhanced activity is dependent on the level of receptor expression. In HEK-293 cells stably expressing N133W, signalling through Gi/o-dependent pathways was also observed. Radioligand binding studies revealed that the affinity for nociceptin of the wild-type ORL1 receptor and the N133W mutant do not differ significantly, suggesting that the ligand binding and signalling functions of constitutively active mutants of G protein-coupled receptors are not necessarily intrinsically linked. In conclusion, our results demonstrate that a mutation in the third transmembrane domain is able to increase the basal signalling activity of the human ORL1 receptor.
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Affiliation(s)
- Kenneth W L Kam
- Department of Biochemistry, Molecular Neuroscience Center, and the Biotechnology Research Institute, Hong Kong University of Science and Technology, Clearwater Bay, Hong Kong, China
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38
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Mosberg HI, Fowler CB. Development and validation of opioid ligand-receptor interaction models: the structural basis of mu vs delta selectivity. THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 2002; 60:329-35. [PMID: 12464111 DOI: 10.1034/j.1399-3011.2002.21061.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Opioid receptor binding conformations for two structurally related, conformationally constrained tetrapeptides, JOM-6 ( micro receptor selective) and JOM-13 (delta receptor selective), were deduced using conformational analysis of these ligands and analogs with additional conformational restrictions. Docking of these ligands in their binding conformations to opioid receptor structural models, based upon the published rhodopsin X-ray structure, implicates specific structural features of the micro and delta receptor ligand binding sites as forming the basis for the micro selectivity of JOM-6 and the delta selectivity of JOM-13. In particular, the presence of E229 in the micro receptor (in place of the corresponding D210 of the delta receptor) causes an adverse electrostatic interaction with C-terminal carboxylate-containing ligands, resulting in the observed preference of ligands with an uncharged C-terminus for the micro receptor. In addition, the requirement that the Phe3 side chain of JOM-13 assume a gauche orientation for optimal delta binding, whereas the Phe3 side chain of JOM-6 must be in a trans orientation for high-affinity micro binding can be largely attributed to the steric effect of replacement of L300 of the delta receptor by W318 of the micro receptor. Testing this hypothesis by examining the binding of JOM-6 and several of its key analogs with specific micro receptor mutants is described. Our initial results are consistent with the proposed ligand-receptor interaction models.
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MESH Headings
- Binding Sites
- Binding, Competitive
- Enkephalins/chemistry
- Enkephalins/metabolism
- Ligands
- Models, Molecular
- Mutagenesis, Site-Directed
- Peptides, Cyclic/chemistry
- Peptides, Cyclic/metabolism
- Phenylalanine/chemistry
- Protein Binding
- Protein Conformation
- Radioligand Assay
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, delta/genetics
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/genetics
- Receptors, Opioid, mu/metabolism
- Structure-Activity Relationship
- Substrate Specificity
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Affiliation(s)
- H I Mosberg
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor 48109-1065, USA.
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39
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Mo Y, Subramanian G, Gao J, Ferguson DM. Cation-pi interactions: an energy decomposition analysis and its implication in delta-opioid receptor-ligand binding. J Am Chem Soc 2002; 124:4832-7. [PMID: 11971733 DOI: 10.1021/ja0174433] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The nature and strength of the cation-pi interaction in protein-ligand binding are modeled by considering a series of nonbonded complexes involving N-substituted piperidines and substituted monocylic aromatics that mimic the delta-opioid receptor-ligand binding. High-level ab initio quantum mechanical calculations confirm the importance of such cation-pi interactions, whose intermolecular interaction energy ranges from -6 to -12 kcal/mol. A better understanding of the electrostatics, polarization, and other intermolecular interactions is obtained by appropriately decomposing the total interaction energy into their individual components. The energy decomposition analysis is also useful for parametrizing existing molecular mechanics force fields that could then account for energetic contributions arising out of cation-pi interactions in biomolecules. The present results further provide a framework for interpreting experimental results from point mutation reported for the delta-opioid receptor.
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Affiliation(s)
- Yirong Mo
- Department of Chemistry, Department of Medicinal Chemistry, and Minnesota Supercomputer Institute, University of Minnesota, Minneapolis, Minnesota 55455, USA.
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40
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Barroso S, Richard F, Nicolas-Ethève D, Kitabgi P, Labbé-Jullié C. Constitutive activation of the neurotensin receptor 1 by mutation of Phe(358) in Helix seven. Br J Pharmacol 2002; 135:997-1002. [PMID: 11861328 PMCID: PMC1573210 DOI: 10.1038/sj.bjp.0704546] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2001] [Revised: 11/21/2001] [Accepted: 12/04/2001] [Indexed: 11/09/2022] Open
Abstract
1. The neurotensin receptor 1, NTS1, is a G protein-coupled receptor with seven transmembrane domains (TM) that mediates most of the known effects of the neuropeptide. Our previous studies have pointed to extracellular loop 3 and adjacent TM7 as being potentially involved in agonist-induced activation of the NTS1. 2. Here we investigated residues in these domains that might be involved in transconformational activation of the rat NTS1. Single amino acid mutated receptors were expressed in COS cells and inositol phosphate (IP) and cyclic AMP productions were studied. 3. The F358A mutation in TM7 resulted in a time- and receptor concentration-dependent increase in spontaneous IP production. At expression levels of 12 pmol mg(-1), agonist-independent IP production was increased 10 fold over basal for the F358A mutant receptor whereas the wild type NTS1 exhibited virtually no spontaneous activity at expression levels of 7.5 pmol mg(-1). 4. Neurotensin remained agonist on the F358A mutant receptor with a maximal effect that amounted to greater than twice basal IP levels. SR 48692 was inverse agonist at the mutant receptor, reversing IP production almost back to the levels measured in wild type NTS1-transfected cells. 5. Cyclic AMP production was not constitutively activated with the F358A mutant receptor but was stimulated by neurotensin with the same concentration dependence as that observed with the wild type NTS1. 6. This is the first report, to our knowledge, of a constitutively active mutant of the NTS1. The data are consistent with TM7 being involved in the transconformational changes that lead to agonist-induced coupling of the NTS1 to Gq.
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Affiliation(s)
- Séverine Barroso
- Institut de Pharmacologie Moléculaire et Cellulaire du CNRS, Université de Nice-Sophia Antipolis, Sophia Antipolis, 660 route des Lucioles, 06560 Valbonne, France
| | - Françoise Richard
- Institut de Pharmacologie Moléculaire et Cellulaire du CNRS, Université de Nice-Sophia Antipolis, Sophia Antipolis, 660 route des Lucioles, 06560 Valbonne, France
| | - Delphine Nicolas-Ethève
- Institut de Pharmacologie Moléculaire et Cellulaire du CNRS, Université de Nice-Sophia Antipolis, Sophia Antipolis, 660 route des Lucioles, 06560 Valbonne, France
| | - Patrick Kitabgi
- Institut de Pharmacologie Moléculaire et Cellulaire du CNRS, Université de Nice-Sophia Antipolis, Sophia Antipolis, 660 route des Lucioles, 06560 Valbonne, France
| | - Catherine Labbé-Jullié
- Institut de Pharmacologie Moléculaire et Cellulaire du CNRS, Université de Nice-Sophia Antipolis, Sophia Antipolis, 660 route des Lucioles, 06560 Valbonne, France
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41
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Skoubis PD, Matthes HW, Walwyn WM, Kieffer BL, Maidment NT. Naloxone fails to produce conditioned place aversion in mu-opioid receptor knock-out mice. Neuroscience 2002; 106:757-63. [PMID: 11682161 DOI: 10.1016/s0306-4522(01)00333-5] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
There is growing evidence that tonic activity of the opioid system may be important in the modulation of affective state. Naloxone produces a conditioned place aversion in rodents, an effect that is centrally mediated. Previous pharmacological data using antagonists with preferential actions at mu-, delta-, and kappa-opioid receptors indicate the importance of the mu-opioid receptor in mediating this effect. We sought to test the mu-opioid receptor selectivity of naloxone aversion using mu-opioid receptor knock-out mice. mu-Opioid receptor knock-out and wild-type mice were tested for naloxone (10 mg/kg, s.c.) aversion using a place conditioning paradigm. As a positive control for associative learning, knock-out mice were tested for conditioned place aversion to a kappa agonist, U50,488H (2 mg/kg, s.c.). Naloxone produced a significant place aversion in wild-type mice, but failed to have any effect in mu-opioid receptor knock-out mice. On the other hand, both knock-out and wild-type mice treated with U50,488H spent significantly less time in the drug-paired chamber compared to their respective vehicle controls. We conclude that the mu-opioid receptor is crucial for the acquisition of naloxone-induced conditioned place aversion. Furthermore, in a separate experiment using C57BL/6 mice, the delta-selective antagonist naltrindole (10 or 30 mg/kg, s.c.) failed to produce conditioned place aversion.Taken together, these data further support the notion that naloxone produces aversion by antagonizing tonic opioid activity at the mu-opioid receptor.
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MESH Headings
- 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer/pharmacology
- Analgesics, Non-Narcotic/pharmacology
- Animals
- Avoidance Learning/drug effects
- Avoidance Learning/physiology
- Brain/drug effects
- Brain/metabolism
- Conditioning, Psychological/drug effects
- Conditioning, Psychological/physiology
- Dose-Response Relationship, Drug
- Habituation, Psychophysiologic/drug effects
- Habituation, Psychophysiologic/physiology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Motor Activity/drug effects
- Motor Activity/physiology
- Naloxone/pharmacology
- Naltrexone/analogs & derivatives
- Naltrexone/pharmacology
- Narcotic Antagonists/pharmacology
- Neurons/drug effects
- Neurons/metabolism
- Opioid Peptides/antagonists & inhibitors
- Opioid Peptides/metabolism
- Phenotype
- Receptors, Opioid, delta/drug effects
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, kappa/drug effects
- Receptors, Opioid, kappa/metabolism
- Receptors, Opioid, mu/deficiency
- Receptors, Opioid, mu/genetics
- Synaptic Transmission/drug effects
- Synaptic Transmission/physiology
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Affiliation(s)
- P D Skoubis
- University of California at Los Angeles, 20024, USA
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42
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Marie J, Richard E, Pruneau D, Paquet JL, Siatka C, Larguier R, Poncé C, Vassault P, Groblewski T, Maigret B, Bonnafous JC. Control of conformational equilibria in the human B2 bradykinin receptor. Modeling of nonpeptidic ligand action and comparison to the rhodopsin structure. J Biol Chem 2001; 276:41100-11. [PMID: 11495910 DOI: 10.1074/jbc.m104875200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
A prototypic study of the molecular mechanisms of activation or inactivation of peptide hormone G protein-coupled receptors was carried out on the human B2 bradykinin receptor. A detailed pharmacological analysis of receptor mutants possessing either increased constitutive activity or impaired activation or ligand recognition allowed us to propose key residues participating in intramolecular interaction networks stabilizing receptor inactive or active conformations: Asn(113) and Tyr(115) (TM III), Trp(256) and Phe(259) (TM VI), Tyr(295) (TM VII) which are homologous of the rhodopsin residues Gly(120), Glu(122), Trp(265), Tyr(268), and Lys(296), respectively. An essential experimental finding was the spatial proximity between Asn(113), which is the cornerstone of inactive conformations, and Trp(256) which plays a subtle role in controlling the balance between active and inactive conformations. Molecular modeling and mutagenesis data showed that Trp(256) and Tyr(295) constitute, together with Gln(288), receptor contact points with original nonpeptidic ligands. It provided an explanation for the ligand inverse agonist behavior on the WT receptor, with underlying restricted motions of TMs III, VI, and VII, and its agonist behavior on the Ala(113) and Phe(256) constitutively activated mutants. These data on the B2 receptor emphasize that conformational equilibria are controlled in a coordinated fashion by key residues which are located at strategic positions for several G protein-coupled receptors. They are discussed in comparison with the recently determined rhodopsin crystallographic structure.
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Affiliation(s)
- J Marie
- INSERM U439, 70 rue de Navacelles 34090 Montpellier, France
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43
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Chen A, Gao ZG, Barak D, Liang BT, Jacobson KA. Constitutive activation of A(3) adenosine receptors by site-directed mutagenesis. Biochem Biophys Res Commun 2001; 284:596-601. [PMID: 11396942 PMCID: PMC3626079 DOI: 10.1006/bbrc.2001.5027] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The objective of this study was to create constitutively active mutant human A(3) adenosine receptors (ARs) using single amino acid replacements, based on findings from other G protein-coupled receptors. A(3) ARs mutated in transmembrane helical domains (TMs) 1, 3, 6, and 7 were expressed in COS-7 cells and subjected to agonist radioligand binding and phospholipase C (PLC) and adenylyl cyclase (AC) assays. Three mutant receptors, A229E in TM6 and R108A and R108K in the DRY motif of TM3, were found to be constitutively active in both functional assays. The potency of the A(3) agonist Cl-IB-MECA (1-chloro-N(6)-(3-iodobenzyl)adenosine-5'-N-methyluronamide) in PLC activation was enhanced by at least an order of magnitude over wild type (EC(50) 951 nM) in R108A and A229E mutant receptors. Cl-IB-MECA was much less potent (>10-fold) in C88F, Y109F, and Y282F and mutants or inactive following double mutation of the DRY motif. The degree of constitutive activation was more pronounced for the AC signaling pathway than for the PLC signaling pathway. The results indicated that specific locations within the TMs proximal to the cytosolic region were responsible for constraining the receptor in a G protein-uncoupled conformation.
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Affiliation(s)
- Aishe Chen
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Zhan-Guo Gao
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Dov Barak
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
- on leave from Israel Institute for Biological Research, Ness Ziona, Israel
| | - Bruce T. Liang
- Department of Medicine, Cardiovascular Division, and Department of Pharmacology University of Pennsylvania Medical Center, Philadelphia, PA 19104, USA
| | - Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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44
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Hill J, Duckworth M, Murdock P, Rennie G, Sabido-David C, Ames RS, Szekeres P, Wilson S, Bergsma DJ, Gloger IS, Levy DS, Chambers JK, Muir AI. Molecular cloning and functional characterization of MCH2, a novel human MCH receptor. J Biol Chem 2001; 276:20125-9. [PMID: 11274220 DOI: 10.1074/jbc.m102068200] [Citation(s) in RCA: 183] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Melanin-concentrating hormone (MCH) is involved in the regulation of feeding and energy homeostasis. Recently, a 353-amino acid splice variant form of the human orphan receptor SLC-1 () (hereafter referred to as MCH(1)) was identified as an MCH receptor. This report describes the cloning and functional characterization of a novel second human MCH receptor, which we designate MCH(2), initially identified in a genomic survey sequence as being homologous to MCH(1) receptors. Using this sequence, a full-length cDNA was generated with an open reading frame of 1023 base pairs, encoding a polypeptide of 340 amino acids, with 38% identity to MCH(1) and with many of the structural features conserved in G protein-coupled receptors. This newly discovered receptor belongs to class 1 (rhodopsin-like) of the G protein-coupled receptor superfamily. HEK293 cells transfected with MCH(2) receptors responded to nanomolar concentrations of MCH with an increase in intracellular Ca(2+) levels and increased cellular extrusion of protons. In addition, fluorescently labeled MCH bound with nanomolar affinity to these cells. The tissue localization of MCH(2) receptor mRNA, as determined by quantitative reverse transcription-polymerase chain reaction, was similar to that of MCH(1) in that both receptors are expressed predominantly in the brain. The discovery of a novel MCH receptor represents a new potential drug target and will allow the further elucidation of MCH-mediated responses.
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Affiliation(s)
- J Hill
- Departments of Molecular Biology, Bioinformatics, Gene Expression Sciences, Computational and Structural Sciences, and Vascular Biology, GlaxoSmithKline, New Frontiers Science Park, Third Avenue, Harlow, Essex CM19 5AW, United Kingdom
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Wang D, Raehal KM, Bilsky EJ, Sadée W. Inverse agonists and neutral antagonists at mu opioid receptor (MOR): possible role of basal receptor signaling in narcotic dependence. J Neurochem 2001; 77:1590-600. [PMID: 11413242 DOI: 10.1046/j.1471-4159.2001.00362.x] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The mu opioid receptor, MOR, displays spontaneous agonist-independent (basal) G protein coupling in vitro. To determine whether basal MOR signaling contributes to narcotic dependence, antagonists were tested for intrinsic effects on basal MOR signaling in vitro and in vivo, before and after morphine pretreatment. Intrinsic effects of MOR ligands were tested by measuring GTPgammaS binding to cell membranes and cAMP levels in intact cells. beta-CNA, C-CAM, BNTX, and nalmefene were identified as inverse agonists (suppressing basal MOR signaling). Naloxone and naltrexone were neutral antagonists (not affecting basal signaling) in untreated cells, whereas inverse agonistic effects became apparent only after morphine pretreatment. In contrast, 6alpha- and 6beta-naltrexol and -naloxol, and 6beta-naltrexamine were neutral antagonists regardless of morphine pretreatment. In an acute and chronic mouse model of morphine-induced dependence, 6beta-naltrexol caused significantly reduced withdrawal jumping compared to naloxone and naltrexone, at doses effective in blocking morphine antinociception. This supports the hypothesis that naloxone-induced withdrawal symptoms result at least in part from suppression of basal signaling activity of MOR in morphine-dependent animals. Neutral antagonists have promise in treatment of narcotic addiction.
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Affiliation(s)
- D Wang
- Department of Biopharmaceutical Sciences and Pharmaceutical Chemistry, and Wheeler Center for Neurobiology of Addiction, University of California San Francisco, 94143-0446, USA
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46
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Abstract
Significant advances have been made in understanding the structure, function, and regulation of opioid receptors and endogenous opioid peptides since their discovery approximately 25 years ago. This review summarizes recent studies aimed at identifying key amino acids that confer ligand selectivity to the opioid receptors and that are critical constituents of the ligand binding sites. A molecular model of the delta receptor based on the crystal structure of rhodopsin is presented. Agonist-induced down regulation of opioid receptors is discussed, highlighting recent evidence for the involvement of the ubiquitin/proteasome system in this process.
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Affiliation(s)
- K Chaturvedi
- Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, NJ 07103, USA
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47
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Gant TM, Riba P, Lee NM. Morphine tolerance in mice is independent of polymorphisms in opioid receptor sequences. Brain Res Bull 2001; 55:59-63. [PMID: 11427338 DOI: 10.1016/s0361-9230(01)00497-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Pharmacogenomics links individual drug response variation to genetic differences, such as single nucleotide polymorphisms (SNPs). In particular, pharmacogenomics will allow clinicians to use genetic diagnostics to predict the response of a patient to a drug. We investigated whether SNPs in opioid receptors correlated with the development of morphine tolerance in mouse strains that showed either high or low tolerance to morphine. Sequencing identified five silent SNPs in the delta opioid receptor that varied from the published sequence in some strains, but which were found in both high and low tolerance strains. The mu and kappa opioid receptor sequences had no SNPs. Taken together, these data definitively demonstrate that morphine tolerance development in mice is independent of opioid receptor sequence.
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Affiliation(s)
- T M Gant
- Geraldine Brush Cancer Research Institute, California Pacific Medical Center Research Institute, San Francisco, CA 94115, USA
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48
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Metzler DE, Metzler CM, Sauke DJ. Chemical Communication Between Cells. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50033-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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49
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Kramer HK, Andria ML, Esposito DH, Simon EJ. Tyrosine phosphorylation of the delta-opioid receptor. Evidence for its role in mitogen-activated protein kinase activation and receptor internalization*. Biochem Pharmacol 2000; 60:781-92. [PMID: 10930532 DOI: 10.1016/s0006-2952(00)00400-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The internalization of G-protein-coupled receptors (GPCRs), including the delta opioid receptor (delta-OR), has been shown to involve the phosphorylation of serine and threonine residues. However, recent studies suggest that these residues may not be the only ones phosphorylated in response to prolonged opioid exposure. Tyrosines also appear important for delta-OR signalling, but it remains unclear whether they undergo phosphorylation. We examined whether the delta-OR, stably expressed in Chinese hamster ovary (CHO-K1) cells, was tyrosine-phosphorylated during prolonged agonist treatment. The epitope-tagged delta-OR was purified by immunoprecipitation, and the presence of phosphorylated tyrosines was detected using anti-phosphotyrosine antibodies. Tyrosine residues in the delta-OR were phosphorylated after exposure to the high-affinity agonist [d-Thr(2)]-Leu-enkephalin-Thr (DTLET) in a time- and concentration-dependent manner. Tyrosine phosphorylation of the delta-OR appeared to require the actions of a Src-like protein tyrosine kinase, since the Src inhibitor 4-amino-5-(4-methylphenyl)-7-(t-butyl)-pyrazolo-[3,4-d]-pyrimidine (PP1) attenuated this response. PP1 also attenuated the DTLET-mediated activation of mitogen-activated protein kinase, as well as rapid delta-OR internalization, but not receptor down-regulation. Finally, only opioid agonists that induce receptor internalization via the clathrin-dependent endosomal pathway stimulated significant tyrosine phosphorylation of the delta-OR protein. Evidence is presented that the delta-OR is tyrosine-phosphorylated, and we suggest how this may have an active role in opioid receptor signalling and regulation.
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Affiliation(s)
- H K Kramer
- Department of Psychiatry, New York University School of Medicine, Millhauser Laboratories, New York, NY 10016, USA.
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50
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Chaturvedi K, Jiang X, Christoffers KH, Chinen N, Bandari P, Raveglia LF, Ronzoni S, Dondio G, Howells RD. Pharmacological profiles of selective non-peptidic delta opioid receptor ligands. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2000; 80:166-76. [PMID: 11038249 DOI: 10.1016/s0169-328x(00)00134-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Several non-peptidic opioids have been synthesized recently as part of a program to develop selective delta receptor agonists. In this study, the affinities of a set of compounds for cloned delta and mu opioid receptors expressed in HEK 293 cell lines were determined by competition analysis of [3H]bremazocine binding to membrane preparations. All compounds studied exhibited high affinity and selectivity, with apparent dissociation constants in the range of 0.6-1.7 nM for the delta opioid receptor and 240-1165 nM for the mu opioid receptor. We next sought to determine which domain of the delta receptor was critical for mediating the highly selective binding by analysis of ligand affinities for mu/delta receptor chimeras. Receptor binding profiles suggested that a critical site of receptor/ligand interaction was located between transmembrane domain 5 (TM5) and TM7 of the delta receptor. Substitution of tryptophan 284, located at the extracellular surface of TM6, with lysine, which is found at the equivalent position in the mu opioid receptor, led to a spectrum of effects on affinities, depending on the ligand tested. Affinities of SB 219825 and SB 222941 were particularly sensitive to the substitution, displaying a 50-fold and 70-fold decrease in affinity, respectively. Activities of the delta receptor-selective agonists were tested in two functional assays. Brief exposure of HEK 293 cells expressing delta opioid receptors with selective ligands induced phosphorylation of MAP kinase, although the non-peptidic ligands were less efficacious than the enkephalin derivative DADL (Tyr-D-Ala-Gly-Phe-D-Leu). Similarly, chronic exposure of HEK 293 cells expressing delta opioid receptors with selective, non-peptidic ligands, with the exception of SB 206848, caused receptor down-regulation, however, the SB compounds were less efficacious than DADL.
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MESH Headings
- Amino Acid Sequence
- Analgesics/metabolism
- Analgesics/pharmacology
- Analgesics, Opioid/metabolism
- Analgesics, Opioid/pharmacology
- Benzomorphans/metabolism
- Benzomorphans/pharmacology
- Binding, Competitive
- Cells, Cultured
- Cloning, Molecular
- Down-Regulation/drug effects
- Down-Regulation/physiology
- Enkephalin, Leucine-2-Alanine/pharmacology
- GTP-Binding Proteins/metabolism
- Heterocyclic Compounds, 4 or More Rings/chemistry
- Heterocyclic Compounds, 4 or More Rings/pharmacology
- Humans
- Indoles/chemistry
- Indoles/pharmacology
- Isoquinolines/chemistry
- Isoquinolines/pharmacology
- Kidney/cytology
- Ligands
- Mitogen-Activated Protein Kinases/metabolism
- Molecular Sequence Data
- Morphine/metabolism
- Morphine/pharmacology
- Mutagenesis, Site-Directed
- Naloxone/pharmacology
- Narcotic Antagonists/pharmacology
- Quinolines/chemistry
- Quinolines/metabolism
- Quinolines/pharmacology
- Radioligand Assay
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, delta/antagonists & inhibitors
- Receptors, Opioid, delta/genetics
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/antagonists & inhibitors
- Receptors, Opioid, mu/genetics
- Tritium
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Affiliation(s)
- K Chaturvedi
- Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, 185 South Orange Avenue, 07103, Newark, NJ, USA
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