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Batebi H, Pérez-Hernández G, Rahman SN, Lan B, Kamprad A, Shi M, Speck D, Tiemann JKS, Guixà-González R, Reinhardt F, Stadler PF, Papasergi-Scott MM, Skiniotis G, Scheerer P, Kobilka BK, Mathiesen JM, Liu X, Hildebrand PW. Mechanistic insights into G-protein coupling with an agonist-bound G-protein-coupled receptor. Nat Struct Mol Biol 2024:10.1038/s41594-024-01334-2. [PMID: 38867113 DOI: 10.1038/s41594-024-01334-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2024] [Accepted: 05/14/2024] [Indexed: 06/14/2024]
Abstract
G-protein-coupled receptors (GPCRs) activate heterotrimeric G proteins by promoting guanine nucleotide exchange. Here, we investigate the coupling of G proteins with GPCRs and describe the events that ultimately lead to the ejection of GDP from its binding pocket in the Gα subunit, the rate-limiting step during G-protein activation. Using molecular dynamics simulations, we investigate the temporal progression of structural rearrangements of GDP-bound Gs protein (Gs·GDP; hereafter GsGDP) upon coupling to the β2-adrenergic receptor (β2AR) in atomic detail. The binding of GsGDP to the β2AR is followed by long-range allosteric effects that significantly reduce the energy needed for GDP release: the opening of α1-αF helices, the displacement of the αG helix and the opening of the α-helical domain. Signal propagation to the Gs occurs through an extended receptor interface, including a lysine-rich motif at the intracellular end of a kinked transmembrane helix 6, which was confirmed by site-directed mutagenesis and functional assays. From this β2AR-GsGDP intermediate, Gs undergoes an in-plane rotation along the receptor axis to approach the β2AR-Gsempty state. The simulations shed light on how the structural elements at the receptor-G-protein interface may interact to transmit the signal over 30 Å to the nucleotide-binding site. Our analysis extends the current limited view of nucleotide-free snapshots to include additional states and structural features responsible for signaling and G-protein coupling specificity.
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Affiliation(s)
- Hossein Batebi
- Universität Leipzig, Medizinische Fakultät, Institut für Medizinische Physik und Biophysik, Leipzig, Germany
- Freie Universität Berlin, Fachbereich Physik, Berlin, Germany
| | - Guillermo Pérez-Hernández
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Berlin, Germany
| | - Sabrina N Rahman
- University of Copenhagen, Department of Drug Design and Pharmacology, Copenhagen, Denmark
| | - Baoliang Lan
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, School of Pharmaceutical Sciences, Tsinghua University, Beijing, China
| | - Antje Kamprad
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Group Structural Biology of Cellular Signaling, Berlin, Germany
| | - Mingyu Shi
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, School of Pharmaceutical Sciences, Tsinghua University, Beijing, China
| | - David Speck
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Group Structural Biology of Cellular Signaling, Berlin, Germany
| | - Johanna K S Tiemann
- Universität Leipzig, Medizinische Fakultät, Institut für Medizinische Physik und Biophysik, Leipzig, Germany
- Novozymes A/S, Lyngby, Denmark
| | - Ramon Guixà-González
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Berlin, Germany
- Department of Biological Chemistry, Institute for Advanced Chemistry of Catalonia (IQAC-CSIC), Barcelona, Spain
| | - Franziska Reinhardt
- Universität Leipzig, Department of Computer Science, Bioinformatics, Leipzig, Germany
| | - Peter F Stadler
- Universität Leipzig, Department of Computer Science, Bioinformatics, Leipzig, Germany
| | - Makaía M Papasergi-Scott
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Georgios Skiniotis
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Patrick Scheerer
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Group Structural Biology of Cellular Signaling, Berlin, Germany
| | - Brian K Kobilka
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Jesper M Mathiesen
- University of Copenhagen, Department of Drug Design and Pharmacology, Copenhagen, Denmark
| | - Xiangyu Liu
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, School of Pharmaceutical Sciences, Tsinghua University, Beijing, China
| | - Peter W Hildebrand
- Universität Leipzig, Medizinische Fakultät, Institut für Medizinische Physik und Biophysik, Leipzig, Germany.
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Berlin, Germany.
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2
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Ferraro M, Decherchi S, De Simone A, Recanatini M, Cavalli A, Bottegoni G. Multi-target dopamine D3 receptor modulators: Actionable knowledge for drug design from molecular dynamics and machine learning. Eur J Med Chem 2019; 188:111975. [PMID: 31940507 DOI: 10.1016/j.ejmech.2019.111975] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 12/02/2019] [Accepted: 12/16/2019] [Indexed: 10/25/2022]
Abstract
Local changes in the structure of G-protein coupled receptors (GPCR) binders largely affect their pharmacological profile. While the sought efficacy can be empirically obtained by introducing local modifications, the underlining structural explanation can remain elusive. Here, molecular dynamics (MD) simulations of the eticlopride-bound inactive state of the Dopamine D3 Receptor (D3DR) have been clustered using a machine learning-based approach in the attempt to rationalize the efficacy change in four congeneric modulators. Accumulating extended MD trajectories of receptor-ligand complexes, we observed how the increase in ligand flexibility progressively destabilized the crystal structure of the inactivated receptor. To prospectively validate this model, a partial agonist was rationally designed based on structural insights and computational modeling, and eventually synthesized and tested. Results turned out to be in line with the predictions. This case study suggests that the investigation of ligand flexibility in the framework of extended MD simulations can assist and inform drug design strategies, highlighting its potential role as a powerful in silico counterpart to functional assays.
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Affiliation(s)
- Mariarosaria Ferraro
- Istituto di Chimica Del Riconoscimento Molecolare, Consiglio Nazionale Delle Ricerche (ICRM-CNR), Via Mario Bianco 9, 20131, Milan, Italy.
| | - Sergio Decherchi
- Computational & Chemical Biology, Italian Institute of Technology, Via Morego 30, 16163, Genoa, Italy.
| | - Alessio De Simone
- Sygnature Discovery Ltd, Bio City, Pennyfoot St, Nottingham NG1 1GR, United Kingdom.
| | - Maurizio Recanatini
- Dept. of Pharmacy and Biotechnology, University of Bologna, Via Belmeloro 6, 40126, Bologna, Italy.
| | - Andrea Cavalli
- Computational & Chemical Biology, Italian Institute of Technology, Via Morego 30, 16163, Genoa, Italy; Dept. of Pharmacy and Biotechnology, University of Bologna, Via Belmeloro 6, 40126, Bologna, Italy.
| | - Giovanni Bottegoni
- School of Pharmacy, University of Birmingham, Sir Robert Aitken Institute for Clinical Research, Edgbaston, B15 2TT, United Kingdom.
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3
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Gao N, Liang T, Yuan Y, Xiao X, Zhao Y, Guo Y, Li M, Pu X. Exploring the mechanism of F282L mutation-caused constitutive activity of GPCR by a computational study. Phys Chem Chem Phys 2018; 18:29412-29422. [PMID: 27735961 DOI: 10.1039/c6cp03710k] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
G-protein-coupled receptors (GPCRs) are important drug targets and generally activated by ligands. However, some experiments found that GPCRs also give rise to constitutive activity through some mutations (viz., CAM), which are usually associated with different kinds of diseases. However, the mechanisms of CAMs and their roles in interactions with drug-ligands are unclear in experiments. Herein, we used microsecond molecular dynamics simulations to study the effect of one important F282L mutation on β2AR in order to address the questions above. With the aid of principle component and correlation analysis, our results revealed that the F282L mutation could increase the instability of the overall structure, increase the dramatic fluctuations of NPxxY and extracellular loops, and decrease restraint of the helices through weakening interhelical H-bonding and correlations between residues, which could partly contribute to the constitutive activity reported by the experiments. The observations from the protein structure network (PSN) analysis indicate that the mutant exhibits less information flow than the wild β2AR and weakens the role of TM5 and TM6 in the signal transmission, but it enhances the impact of TM3 on the orthosteric pathway and TM4 on the allosteric one. In addition, the results from the virtual screening reveal that the mutant prefers to select agonists rather than antagonists, similar to the active state but opposite of the inactive state, further confirming that the F282L mutation advances the activation of β2AR. Our observations provide valuable information for understanding the mechanism of the mutation-caused constitutive activity of GPCR and related drug-design.
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Affiliation(s)
- Nan Gao
- Faculty of Chemistry, Sichuan University, Chengdu, Sichuan 610064, People's Republic of China.
| | - Tao Liang
- Faculty of Chemistry, Sichuan University, Chengdu, Sichuan 610064, People's Republic of China.
| | - Yuan Yuan
- College of Management, Southwest University for Nationalities, Chengdu 610041, P. R. China
| | - Xiuchan Xiao
- Department of Architecture and Environmental Engineering, Chengdu Technological University, Chengdu, Sichuan 611730, China
| | - Yihuan Zhao
- Faculty of Chemistry, Sichuan University, Chengdu, Sichuan 610064, People's Republic of China.
| | - Yanzhi Guo
- Faculty of Chemistry, Sichuan University, Chengdu, Sichuan 610064, People's Republic of China.
| | - Menglong Li
- Faculty of Chemistry, Sichuan University, Chengdu, Sichuan 610064, People's Republic of China.
| | - Xuemei Pu
- Faculty of Chemistry, Sichuan University, Chengdu, Sichuan 610064, People's Republic of China.
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4
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Rose AS, Zachariae U, Grubmüller H, Hofmann KP, Scheerer P, Hildebrand PW. Role of Structural Dynamics at the Receptor G Protein Interface for Signal Transduction. PLoS One 2015; 10:e0143399. [PMID: 26606751 PMCID: PMC4659624 DOI: 10.1371/journal.pone.0143399] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 11/04/2015] [Indexed: 11/19/2022] Open
Abstract
GPCRs catalyze GDP/GTP exchange in the α-subunit of heterotrimeric G proteins (Gαßγ) through displacement of the Gα C-terminal α5 helix, which directly connects the interface of the active receptor (R*) to the nucleotide binding pocket of G. Hydrogen-deuterium exchange mass spectrometry and kinetic analysis of R* catalysed G protein activation have suggested that displacement of α5 starts from an intermediate GDP bound complex (R*•GGDP). To elucidate the structural basis of receptor-catalysed displacement of α5, we modelled the structure of R*•GGDP. A flexible docking protocol yielded an intermediate R*•GGDP complex, with a similar overall arrangement as in the X-ray structure of the nucleotide free complex (R*•Gempty), however with the α5 C-terminus (GαCT) forming different polar contacts with R*. Starting molecular dynamics simulations of GαCT bound to R* in the intermediate position, we observe a screw-like motion, which restores the specific interactions of α5 with R* in R*•Gempty. The observed rotation of α5 by 60° is in line with experimental data. Reformation of hydrogen bonds, water expulsion and formation of hydrophobic interactions are driving forces of the α5 displacement. We conclude that the identified interactions between R* and G protein define a structural framework in which the α5 displacement promotes direct transmission of the signal from R* to the GDP binding pocket.
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Affiliation(s)
- Alexander S. Rose
- Institute of Medical Physics and Biophysics (CC2), Universitätsmedizin Berlin, Charitéplatz 1, 10098, Berlin, Germany
- Team ProteiInformatics, Universitätsmedizin Berlin, Charitéplatz 1, 10098, Berlin, Germany
| | - Ulrich Zachariae
- Dep. of Theoretical and Computational Biophysics, Max-Planck-Institute for Biophysical Chemistry, 37077, Göttingen, Germany
- Computational Biology, School of Life Sciences, and Physics, School of Science and Engineering, University of Dundee, Dow Street, Dundee, DD1 5EH, United Kingdom
| | - Helmut Grubmüller
- Dep. of Theoretical and Computational Biophysics, Max-Planck-Institute for Biophysical Chemistry, 37077, Göttingen, Germany
| | - Klaus Peter Hofmann
- Institute of Medical Physics and Biophysics (CC2), Universitätsmedizin Berlin, Charitéplatz 1, 10098, Berlin, Germany
- Centre of Biophysics and Bioinformatics, Humboldt-Universität zu Berlin, Invalidenstrasse 42, 10115, Berlin, Germany
| | - Patrick Scheerer
- Institute of Medical Physics and Biophysics (CC2), Universitätsmedizin Berlin, Charitéplatz 1, 10098, Berlin, Germany
- Team Protein X-ray Crystallography and Signal Transduction, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10098, Berlin, Germany
| | - Peter W. Hildebrand
- Institute of Medical Physics and Biophysics (CC2), Universitätsmedizin Berlin, Charitéplatz 1, 10098, Berlin, Germany
- Team ProteiInformatics, Universitätsmedizin Berlin, Charitéplatz 1, 10098, Berlin, Germany
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5
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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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Sun X, Ågren H, Tu Y. Microsecond Molecular Dynamics Simulations Provide Insight into the Allosteric Mechanism of the Gs Protein Uncoupling from the β2 Adrenergic Receptor. J Phys Chem B 2014; 118:14737-44. [PMID: 25453446 DOI: 10.1021/jp506579a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Experiments have revealed that in the β(2) adrenergic receptor (β(2)AR)-Gs protein complex the α subunit (Gαs) of the Gs protein can adopt either an "open" conformation or a "closed" conformation. In the "open" conformation the Gs protein prefers to bind to the β(2)AR, while in the "closed" conformation an uncoupling of the Gs protein from the β(2)AR occurs. However, the mechanism that leads to such different behaviors of the Gs protein remains unclear. Here, we report results from microsecond molecular dynamics simulations and community network analysis of the β(2)AR-Gs complex with Gαs in the "open" and "closed" conformations. We observed that the complex is stabilized differently in the "open" and "closed" conformations. The community network analysis reveals that in the "closed" conformation there exists strong allosteric communication between the β(2)AR and Gβγ, mediated by Gαs. We suggest that such high information flows are necessary for the Gs protein uncoupling from the β(2)AR.
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Affiliation(s)
- Xianqiang Sun
- Division of Theoretical Chemistry and Biology, School of Biotechnology, KTH Royal Institute of Technology , S-106 91 Stockholm, Sweden
| | - Hans Ågren
- Division of Theoretical Chemistry and Biology, School of Biotechnology, KTH Royal Institute of Technology , S-106 91 Stockholm, Sweden
| | - Yaoquan Tu
- Division of Theoretical Chemistry and Biology, School of Biotechnology, KTH Royal Institute of Technology , S-106 91 Stockholm, Sweden
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7
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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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8
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Kling RC, Lanig H, Clark T, Gmeiner P. Active-state models of ternary GPCR complexes: determinants of selective receptor-G-protein coupling. PLoS One 2013; 8:e67244. [PMID: 23826246 PMCID: PMC3691126 DOI: 10.1371/journal.pone.0067244] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 05/16/2013] [Indexed: 11/29/2022] Open
Abstract
Based on the recently described crystal structure of the β2 adrenergic receptor - Gs-protein complex, we report the first molecular-dynamics simulations of ternary GPCR complexes designed to identify the selectivity determinants for receptor-G-protein binding. Long-term molecular dynamics simulations of agonist-bound β2AR-Gαs and D2R-Gαi complexes embedded in a hydrated bilayer environment and computational alanine-scanning mutagenesis identified distinct residues of the N-terminal region of intracellular loop 3 to be crucial for coupling selectivity. Within the G-protein, specific amino acids of the α5-helix, the C-terminus of the Gα-subunit and the regions around αN-β1 and α4-β6 were found to determine receptor recognition. Knowledge of these determinants of receptor-G-protein binding selectivity is essential for designing drugs that target specific receptor/G-protein combinations.
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MESH Headings
- Alanine/genetics
- Amino Acid Sequence
- Binding Sites
- Dopamine/metabolism
- GTP-Binding Protein alpha Subunits, Gi-Go/chemistry
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- GTP-Binding Proteins/metabolism
- Histidine/metabolism
- Ligands
- Models, Biological
- Molecular Dynamics Simulation
- Molecular Sequence Data
- Multiprotein Complexes/metabolism
- Mutagenesis
- Protein Structure, Secondary
- Receptors, Adrenergic, beta-2/chemistry
- Receptors, Adrenergic, beta-2/metabolism
- Receptors, Dopamine/chemistry
- Receptors, Dopamine/metabolism
- Receptors, G-Protein-Coupled/chemistry
- Receptors, G-Protein-Coupled/metabolism
- Sequence Alignment
- Structural Homology, Protein
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Affiliation(s)
- Ralf C. Kling
- Department of Chemistry and Pharmacy, Emil Fischer Center, Friedrich Alexander University, Erlangen, Germany
- Department of Chemistry and Pharmacy, Computer Chemistry Center, Friedrich Alexander University, Erlangen, Germany
| | - Harald Lanig
- Department of Chemistry and Pharmacy, Computer Chemistry Center, Friedrich Alexander University, Erlangen, Germany
| | - Timothy Clark
- Department of Chemistry and Pharmacy, Computer Chemistry Center, Friedrich Alexander University, Erlangen, Germany
- Centre for Molecular Design, University of Portsmouth, King Henry Building, Portsmouth, United Kingdom
| | - Peter Gmeiner
- Department of Chemistry and Pharmacy, Emil Fischer Center, Friedrich Alexander University, Erlangen, Germany
- * E-mail:
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9
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Taddese B, Simpson LM, Wall ID, Blaney FE, Reynolds CA. Modeling Active GPCR Conformations. Methods Enzymol 2013; 522:21-35. [DOI: 10.1016/b978-0-12-407865-9.00002-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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10
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Abstract
A third of marketed drugs act by binding to a G-protein-coupled receptor (GPCR) and either triggering or preventing receptor activation. Although recent crystal structures have provided snapshots of both active and inactive functional states of GPCRs, these structures do not reveal the mechanism by which GPCRs transition between these states. Here we propose an activation mechanism for the β(2)-adrenergic receptor, a prototypical GPCR, based on atomic-level simulations in which an agonist-bound receptor transitions spontaneously from the active to the inactive crystallographically observed conformation. A loosely coupled allosteric network, comprising three regions that can each switch individually between multiple distinct conformations, links small perturbations at the extracellular drug-binding site to large conformational changes at the intracellular G-protein-binding site. Our simulations also exhibit an intermediate that may represent a receptor conformation to which a G protein binds during activation, and suggest that the first structural changes during receptor activation often take place on the intracellular side of the receptor, far from the drug-binding site. By capturing this fundamental signaling process in atomic detail, our results may provide a foundation for the design of drugs that control receptor signaling more precisely by stabilizing specific receptor conformations.
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11
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Rosenbaum DM, Zhang C, Lyons JA, Holl R, Aragao D, Arlow DH, Rasmussen SGF, Choi HJ, Devree BT, Sunahara RK, Chae PS, Gellman SH, Dror RO, Shaw DE, Weis WI, Caffrey M, Gmeiner P, Kobilka BK. Structure and function of an irreversible agonist-β(2) adrenoceptor complex. Nature 2011; 469:236-40. [PMID: 21228876 PMCID: PMC3074335 DOI: 10.1038/nature09665] [Citation(s) in RCA: 612] [Impact Index Per Article: 47.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Accepted: 11/11/2010] [Indexed: 12/12/2022]
Abstract
G protein-coupled receptors (GPCRs) are eukaryotic integral membrane proteins that modulate biological function by initiating cellular signaling in response to chemically diverse agonists. Despite recent progress in the structural biology of GPCRs1, the molecular basis for agonist binding and allosteric modulation of these proteins is poorly understood. Structural knowledge of agonist-bound states is essential for deciphering the mechanism of receptor activation, and for structure-guided design and optimization of ligands. However, the crystallization of agonist-bound GPCRs has been hampered by modest affinities and rapid off-rates of available agonists. Using the inactive structure of the human β2 adrenergic receptor (β2AR) as a guide, we designed a β2AR agonist that can be covalently tethered to a specific site on the receptor through a disulfide bond. The covalent β2AR-agonist complex forms efficiently, and is capable of activating a heterotrimeric G protein. We crystallized a covalent agonist-bound β2AR-T4L fusion protein in lipid bilayers through the use of the lipidic mesophase method2, and determined its structure at 3.5 Å resolution. A comparison to the inactive structure and an antibody-stabilized active structure (companion paper3) shows how binding events at both the extracellular and intracellular surfaces are required to stabilize an active conformation of the receptor. The structures are in agreement with long-timescale (up to 30 μs) molecular dynamics simulations showing that an agonist-bound active conformation spontaneously relaxes to an inactive-like conformation in the absence of a G protein or stabilizing antibody.
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Affiliation(s)
- Daniel M Rosenbaum
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 279 Campus Drive, Stanford, California 94305, USA
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12
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Concerted interconversion between ionic lock substates of the beta(2) adrenergic receptor revealed by microsecond timescale molecular dynamics. Biophys J 2010; 98:76-84. [PMID: 20074514 DOI: 10.1016/j.bpj.2009.09.046] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2009] [Revised: 09/17/2009] [Accepted: 09/21/2009] [Indexed: 01/28/2023] Open
Abstract
The recently solved crystallographic structures for the A(2A) adenosine receptor and the beta(1) and beta(2) adrenergic receptors have shown important differences between members of the class-A G-protein-coupled receptors and their archetypal model, rhodopsin, such as the apparent breaking of the ionic lock that stabilizes the inactive structure. Here, we characterize a 1.02 mus all-atom simulation of an apo-beta(2) adrenergic receptor that is missing the third intracellular loop to better understand the inactive structure. Although we find that the structure is remarkably rigid, there is a rapid influx of water into the core of the protein, as well as a slight expansion of the molecule relative to the crystal structure. In contrast to the x-ray crystal structures, the ionic lock rapidly reforms, although we see an activation-precursor-like event wherein the ionic lock opens for approximately 200 ns, accompanied by movements in the transmembrane helices associated with activation. When the lock reforms, we see the structure return to its inactive conformation. We also find that the ionic lock exists in three states: closed (or locked), semi-open with a bridging water molecule, and open. The interconversion of these states involves the concerted motion of the entire protein. We characterize these states and the concerted motion underlying their interconversion. These findings may help elucidate the connection between key local events and the associated global structural changes during activation.
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13
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Identification of two distinct inactive conformations of the beta2-adrenergic receptor reconciles structural and biochemical observations. Proc Natl Acad Sci U S A 2009; 106:4689-94. [PMID: 19258456 DOI: 10.1073/pnas.0811065106] [Citation(s) in RCA: 245] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Fully understanding the mechanisms of signaling proteins such as G protein-coupled receptors (GPCRs) will require the characterization of their conformational states and the pathways connecting those states. The recent crystal structures of the beta(2)- and beta(1)-adrenergic receptors in a nominally inactive state constituted a major advance toward this goal, but also raised new questions. Although earlier biochemical observations had suggested that these receptors possessed a set of contacts between helices 3 and 6, known as the ionic lock, which was believed to form a molecular switch for receptor activation, the crystal structures lacked these contacts. The unexpectedly broken ionic lock has raised questions about the true conformation(s) of the inactive state and the role of the ionic lock in receptor activation and signaling. To address these questions, we performed microsecond-timescale molecular dynamics simulations of the beta(2)-adrenergic receptor (beta(2)AR) in multiple wild-type and mutant forms. In wild-type simulations, the ionic lock formed reproducibly, bringing the intracellular ends of helices 3 and 6 together to adopt a conformation similar to that found in inactive rhodopsin. Our results suggest that inactive beta(2)AR exists in equilibrium between conformations with the lock formed and the lock broken, whether or not the cocrystallized ligand is present. These findings, along with the formation of several secondary structural elements in the beta(2)AR loops during our simulations, may provide a more comprehensive picture of the inactive state of the beta-adrenergic receptors, reconciling the crystal structures with biochemical studies.
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Zamah AM, Delahunty M, Luttrell LM, Lefkowitz RJ. Protein kinase A-mediated phosphorylation of the beta 2-adrenergic receptor regulates its coupling to Gs and Gi. Demonstration in a reconstituted system. J Biol Chem 2002; 277:31249-56. [PMID: 12063255 DOI: 10.1074/jbc.m202753200] [Citation(s) in RCA: 141] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
While classically viewed as a prototypic G(s) and adenylyl cyclase-coupled G protein-coupled receptor, recent studies have indicated that some aspects of beta(2)-adrenergic receptor (beta(2)-AR) signaling are inhibited by pertussis toxin, indicating that they are mediated by G(i)/G(o) proteins. These signals include activation of ERK MAPKs and Akt activation, as well as hypertrophic and anti-apoptotic pathways in cardiac myocytes. Studies in cultured cells have suggested the hypothesis that protein kinase A (PKA)-mediated phosphorylation of the beta(2)-AR regulates its coupling specificity with respect to G(s) and G(i). Using a Chinese hamster ovary cell system, we show that mutant beta(2)-ARs with Ala substituted for Ser at consensus PKA sites stimulate robust cyclic AMP accumulation (G(s)) but are unable to activate ERK (G(i)). In contrast, Ser --> Asp mutants are dramatically impaired in their ability to activate adenylyl cyclase but are significantly more active than wild type receptor in activating ERK. Activation of adenylyl cyclase by wild type and Ser --> Ala mutant receptors is not altered by pertussis toxin, whereas adenylyl cyclase stimulated through the Ser --> Asp mutant is enhanced. Activation of ERK by wild type and Ser --> Asp receptors is inhibited by pertussis toxin. To further rigorously test the hypothesis, we utilized a completely reconstituted system of purified recombinant wild type and PKA phosphorylation site mutant beta(2)-ARs and heterotrimeric G(s) and G(i). G protein coupling was measured by receptor-mediated stimulation of GTPgammaS binding to the G protein. PKA-mediated phosphorylation of the beta(2)-AR significantly decreased its ability to couple to G(s), while simultaneously dramatically increasing its ability to couple to G(i). These results are reproduced when a purified recombinant Ser --> Asp mutant beta(2)-AR is tested, whereas the Ser --> Ala receptor resembles the unphosphorylated wild type. These results provide strong experimental support for the idea that PKA-mediated phosphorylation of the beta(2)-adrenergic receptor switches its predominant coupling from G(s) to G(i).
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Affiliation(s)
- A Musa Zamah
- Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, USA
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15
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Abstract
Heterotrimeric G proteins in vertebrates constitute a family molecular switches that transduce the activation of a populous group of cell-surface receptors to a group of diverse effector units. The receptors include the photopigments such as rhodopsin and prominent families such as the adrenergic, muscarinic acetylcholine, and chemokine receptors involved in regulating a broad spectrum of responses in humans. Signals from receptors are sensed by heterotrimeric G proteins and transduced to effectors such as adenylyl cyclases, phospholipases, and various ion channels. Physiological regulation of G protein-linked receptors allows for integration of signals that directly or indirectly effect the signaling from receptor-->G protein-->effector(s). Steroid hormones can regulate signaling via transcriptional control of the activities of the genes encoding members of G protein-linked pathways. Posttranscriptional mechanisms are under physiological control, altering the stability of preexisting mRNA and affording an additional level for regulation. Protein phosphorylation, protein prenylation, and proteolysis constitute major posttranslational mechanisms employed in the physiological regulation of G protein-linked signaling. Drawing upon mechanisms at all three levels, physiological regulation permits integration of demands placed on G protein-linked signaling.
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Affiliation(s)
- A J Morris
- Department of Molecular Pharmacology, Diabetes and Metabolic Diseases Research Center, University Medical Center, State University of New York/Stony Brook, Stony Brook, New York 11794-8651, USA
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16
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LeVine H. Structural features of heterotrimeric G-protein-coupled receptors and their modulatory proteins. Mol Neurobiol 1999; 19:111-49. [PMID: 10371466 DOI: 10.1007/bf02743657] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Over the past 20 years, the general mechanism for signaling through 7-transmembrane helix receptors coupled to GTP hydrolysis has been worked out. Although similar in overall organization, subtype variability and subcellular localization of components have built in considerable signaling specificity. Atomic resolution structures for many of the components have delineated the domain organization of these complex proteins and have given physical form to the idea of subtype specificity. This review describes what is known about the physical structures of the 7-transmembrane helix receptors, the heterotrimeric GTP binding coupling proteins, the adenylate cyclase and phospholipase C effector proteins, and signaling modulatory proteins, such as arrestin, phosducin, recoverin-type myristoyl switch proteins, and the pleckstrin homology domain of G-protein receptor kinase-2. These images allow experimenters to contemplate the details of the supramolecular organization of the multiprotein complexes involved in the transmission of signals across the cellular lipid bilayer.
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Affiliation(s)
- H LeVine
- Parke-Davis Pharmaceutical Research Division of Warner-Lambert Company, Ann Arbor, MI 48105, USA
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17
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Frazier WA, Gao AG, Dimitry J, Chung J, Brown EJ, Lindberg FP, Linder ME. The thrombospondin receptor integrin-associated protein (CD47) functionally couples to heterotrimeric Gi. J Biol Chem 1999; 274:8554-60. [PMID: 10085089 DOI: 10.1074/jbc.274.13.8554] [Citation(s) in RCA: 132] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Integrin-associated protein (IAP; CD47) is a thrombospondin receptor that forms a signaling complex with beta3 integrins resulting in enhanced alphavbeta3-dependent cell spreading and chemotaxis and, in platelets, alphaIIbbeta3-dependent spreading and aggregation. These actions of CD47 are all specifically abrogated by pertussis toxin treatment of cells. Here we report that CD47, its beta3 integrin partner, and Gi proteins form a stable, detergent-soluble complex that can be recovered by immunoprecipitation and affinity chromatography. Gialpha is released from this complex by treatment with GTP or AlF4. GTP and AlF4 also reduce the binding of CD47 to its agonist peptide (4N1K) derived from thrombospondin, indicating a direct association of CD47 with Gi. 4N1K peptide causes a rapid decrease in intraplatelet cyclic AMP levels, a Gi-dependent event necessary for aggregation. Finally, 4N1K stimulates the binding of GTPgamma35S to membranes from cells expressing IAP and alphavbeta3. This functional coupling of CD47 to heterotrimeric G proteins provides a mechanistic explanation for the biological effects of CD47 in a wide variety of systems.
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Affiliation(s)
- W A Frazier
- Departments of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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18
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Weill C, Autelitano F, Guenet C, Heitz F, Goeldner M, Ilien B. Pharmacological and structural integrity of muscarinic M2 acetylcholine receptors produced in Sf9 insect cells. Eur J Pharmacol 1997; 333:269-78. [PMID: 9314044 DOI: 10.1016/s0014-2999(97)01139-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Muscarinic acetylcholine receptors (human m2 subtype), expressed in Sf9 cells, using the baculovirus system, were purified and found to display the expected ligand binding properties, whether membrane-bound or affinity-purified. The purified recombinant receptors were specifically photolabelled with p-N,N-[3H]dimethylamino and p-N,N-[3H]dibutylamino benzene diazonium derivatives. Electrophoretic patterns for covalent radioactive incorporation of the probes were essentially similar to those for [3H]propylbenzilylcholine mustard-labelled receptor sites but were dependent on the infection time of Sf9 cells. Pharmacological properties of the recombinant receptors being unaltered did not reflect structural integrity of the protein as substantial proteolytic fragmentation was detected at a prolonged infection time, i.e., at the highest level of expression. Selection of overexpression conditions, as illustrated here for muscarinic receptors, thus requires not only pharmacological controls, but also analysis of the covalently labelled protein under strongly dissociating conditions.
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Affiliation(s)
- C Weill
- Laboratoire de Chimie Bio-Organique, U.R.A. 1386 C.N.R.S., Faculté de Pharmacie, Université Louis Pasteur, Illkirch, France
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19
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Helmreich EJ, Hofmann KP. Structure and function of proteins in G-protein-coupled signal transfer. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1286:285-322. [PMID: 8982287 DOI: 10.1016/s0304-4157(96)00013-5] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- E J Helmreich
- Department of Clinical Biochemistry and Pathobiochemistry, University of Würzburg, Germany
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20
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Luxembourg A. Anti-peptide monoclonal antibodies to the beta-adrenergic receptor: use in purification of beta receptor. Hybridoma (Larchmt) 1995; 14:261-4. [PMID: 7590789 DOI: 10.1089/hyb.1995.14.261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
This article describes a new immunopurification procedure based on monoclonal antibodies raised against peptides of the carboxy-terminal region of the turkey beta-adrenergic receptor. This procedure constitutes a significant purification step of recombinant beta-adrenergic receptors expressed in baculovirus-infected Sf9 cells, and allows the recovery of receptors able to activate Gs in phospholipid vesicles. Additionally, this procedure can be combined with affinity chromatography to yield nearly homogeneous receptor.
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Affiliation(s)
- A Luxembourg
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, USA
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21
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Abstract
Currently known disease-causing mutations in G protein coupled receptors are reviewed and discussed in conjunction with other naturally occurring receptor mutations. Special emphasis is made on opsin, vasopressin and MSH receptor mutations and what they tell are beginning to tell us about the inner workings of this superfamily of signalling molecules.
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Affiliation(s)
- M Birnbaumer
- Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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22
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Nakata H, Kameyama K, Haga K, Haga T. Location of agonist-dependent-phosphorylation sites in the third intracellular loop of muscarinic acetylcholine receptors (m2 subtype). EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 220:29-36. [PMID: 8119296 DOI: 10.1111/j.1432-1033.1994.tb18595.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Muscarinic acetylcholine receptors (mAChR, human m2 subtype) expressed in Sf9 (Spodoptera frugiperda) cells using the baculovirus system were purified and subjected to phosphorylation by a mAChR kinase, which was partially purified from porcine cerebrum. Two bands with apparent molecular masses of 59 kDa and 39 kDa as determined by SDS/PAGE were found to be phosphorylated in an agonist-dependent manner. Both bands were labeled by the irreversible muscarinic ligand [3H]propylbenzilylcholine mustard. Molecular masses of the [32P]phosphorylated or [3H]propylbenzilylcholine-mustard-labeled bands decreased following treatment with N-glycanase. The 59-kDa and 39-kDa bands were converted to 52-kDa and 32-kDa bands, respectively, indicating that both the 59-kDa and 39-kDa bands contain the amino-terminal region where glycosylation sites are present. The ratio of incorporated [32P]phosphate and bound [3H]propylbenzilylcholine mustard was essentially the same for the 59-kDa and 39-kDa bands, indicating that all the phosphorylation sites reside in the sequence of 39 kDa from the amino-terminal region. The amounts of incorporated [32P]phosphate were estimated to be 10-11/receptor, with 7-8 serine and 3-4 threonine, but no phosphorylated tyrosine residues. Further treatment of [32P]phosphorylated or [3H]propylbenzilylcholine-mustard-labeled receptors with V8 protease indicated that the phosphorylation sites were not present in 30-kDa amino-terminal segment. These results indicate that the phosphorylation sites are localized in the range 30-39 kDa from the amino terminus, which consists of primarily the central part of the third intracellular loop. Consistent with this conclusion, a fusion protein containing glutathione S-transferase linked to a peptide corresponding to residues 227-324 of the central part of the third intracellular loop was found to be phosphorylated by the mAChR kinase in a heparin-sensitive manner.
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Affiliation(s)
- H Nakata
- Department of Biochemistry, Faculty of Medicine, University of Tokyo, Japan
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23
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Zhang D, Weinstein H. Polarity conserved positions in transmembrane domains of G-protein coupled receptors and bacteriorhodopsin. FEBS Lett 1994; 337:207-12. [PMID: 8287978 DOI: 10.1016/0014-5793(94)80274-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The polarity of residues at certain positions in the transmembrane domains of G-protein coupled receptors (GPCR) is found to be conserved, and to indicate the pattern of specific helix-helix packing of the helices. A concept of polarity conserved positions (PCP) is proposed to describe this conserved property, and is applied to obtain insight into the structural features of the transmembrane proteins. The common pattern of PCPs for GPCRs indicates that they share a similar packing arrangement of their transmembrane helix bundles. For proteins in the bacteriorhodopsin family the PCP pattern suggests a common packing arrangement that differs from that of GPCRs, in agreement with experimental data. This difference in the packing arrangement underscores the shortcomings of a BR template for the construction of molecular models of GPCRs.
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Affiliation(s)
- D Zhang
- Department of Physiology and Biophysics, Mount Sinai School of Medicine of the City University of New York, NY 10029
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24
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Fraser CM, Lee NH, Pellegrino SM, Kerlavage AR. Molecular properties and regulation of G-protein-coupled receptors. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1994; 49:113-56. [PMID: 7863005 DOI: 10.1016/s0079-6603(08)60049-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- C M Fraser
- Institute for Genomic Research, Gaithersburg, Maryland 20878
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25
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Abstract
Adrenergic receptors for adrenaline and noradrenaline belong to the large multigenic family of receptors coupled to GTP-binding proteins. Three pharmacologic types have been identified: alpha 1-, alpha 2-, and beta-adrenergic receptors. Each of these has three subtypes, characterized by both structural and functional differences. The alpha 2 and beta receptors are coupled negatively and positively, respectively, to adenylyl cyclase via Gi or Gs regulatory proteins, and the alpha 1 receptors modulate phospholipase C via the Go protein. Subtype expression is regulated at the level of the gene, the mRNA, and the protein through various transcriptional and postsynthetic mechanisms. Adrenergic receptors constitute, after rhodopsin, one of the best studied models for the other receptors coupled to G proteins that are likely to display similar structural and functional properties.
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Affiliation(s)
- A D Strosberg
- Laboratoire d'Immuno-Pharmacologie Moléculaire, Institut Cochin de Génétique Moléculaire, Paris, France
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26
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Phosphorylation and desensitization of human m2 muscarinic cholinergic receptors by two isoforms of the beta-adrenergic receptor kinase. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)38697-1] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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27
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Okamoto T, Nishimoto I. Detection of G protein-activator regions in M4 subtype muscarinic, cholinergic, and alpha 2-adrenergic receptors based upon characteristics in primary structure. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42449-0] [Citation(s) in RCA: 114] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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28
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Cerione RA. Reconstitution of receptor/GTP-binding protein interactions. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1071:473-501. [PMID: 1661159 DOI: 10.1016/0304-4157(91)90007-j] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- R A Cerione
- Department of Pharmacology, Cornell University, Ithaca, NY 14853
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29
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Abstract
1. The visual transduction system of the vertebrate retina is a well-studied model for biochemical and molecular studies of signal transduction. The structure and function of rhodopsin, a prototypical G protein-coupled receptor, and transducin or Gt, the photoreceptor G protein, have been particularly well studied. Mechanisms of rhodopsin-Gt interaction are discussed in this review. 2. The visual pigment rhodopsin contains a chromophore, and thus conformational changes leading to activation can be monitored spectroscopically. A model of the conformational changes in the activated receptor is presented based on biophysical and biochemical data. 3. The current information on sites of interaction on receptors and cognate G proteins is summarized. Studies using synthetic peptides from amino acid sequences corresponding to Gt and rhodopsin have provided information on the sites of rhodopsin-Gt interaction. Synthetic peptides from the carboxyl terminal region of alpha t mimic Gt by stabilizing the active conformation of rhodopsin, Metarhodopsin II. 4. The conformation of one such peptide when it is bound to Metarhodopsin II was determined by 2D NMR. The model based on the NMR data was tested using peptide analogs predicted to stabilize or break the structure. These studies yield molecular insight into why toxin-treated and mutant G proteins are uncoupled from receptors.
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Affiliation(s)
- H E Hamm
- Department of Physiology and Biophysics, University of Illinois College of Medicine, Chicago 60680
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30
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Westkaemper RB, Glennon RA. Approaches to molecular modeling studies and specific application to serotonin ligands and receptors. Pharmacol Biochem Behav 1991; 40:1019-31. [PMID: 1816556 DOI: 10.1016/0091-3057(91)90122-i] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Molecular modeling studies are useful in as much as they may allow us to understand the activity and selectivity of currently existing agents, and, furthermore, may aid in the design of completely novel therapeutic agents. There are two basic modeling strategies: the ligand-ligand approach and the ligand-receptor approach. Both approaches possess certain inherent advantages and disadvantages and, in addition, make certain assumptions about the agents and/or receptors being investigated. Keeping with the spirit of this minisymposium, we describe these two approaches, their general usefulness, and their limitations. Using serotonin (5-HT) receptors as a focal point, we review and provide novel examples of molecular modeling studies involving both strategies. Presented for the first time are examples of ligand-receptor models to account for the binding of serotonergic agents at 5-HT2 and 5-HT1C receptors.
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Affiliation(s)
- R B Westkaemper
- Department of Medicinal Chemistry, School of Pharmacy, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298
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31
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Okamoto T, Murayama Y, Hayashi Y, Inagaki M, Ogata E, Nishimoto I. Identification of a Gs activator region of the beta 2-adrenergic receptor that is autoregulated via protein kinase A-dependent phosphorylation. Cell 1991; 67:723-30. [PMID: 1657404 DOI: 10.1016/0092-8674(91)90067-9] [Citation(s) in RCA: 232] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We have localized a G protein activator region of the human beta 2-adrenergic receptor to region beta III-2 (from Arg259 to Lys273). The synthetic beta III-2, corresponding to the C-terminal end of the third cytoplasmic loop, activates Gs at nanomolar concentrations and weakly activates Gi. beta III-2 activates adenylyl cyclase at nanomolar concentrations in wild-type S49 lymphoma membranes, but not in membranes of unc mutant S49 cells, in which Gs is uncoupled from beta-adrenergic stimulation. Phosphorylation of beta III-2 by cAMP-dependent protein kinase A, which is involved in the desensitization of the beta-adrenergic receptor from Gs, drastically reduces the effect of beta III-2 on Gs while potentiating its action on Gi, resulting in a total loss of adenylyl cyclase-stimulating activity. These findings indicate that this receptor sequence is a multipotential G protein activator whose G protein specificity is regulated by protein kinase A.
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Affiliation(s)
- T Okamoto
- Fourth Department of Internal Medicine, University of Tokyo School of Medicine, Japan
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32
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Higashijima T, Ross E. Mapping of the mastoparan-binding site on G proteins. Cross-linking of [125I-Tyr3,Cys11]mastoparan to Go. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)98949-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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33
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Lanier S, Downing S, Duzic E, Homcy C. Isolation of rat genomic clones encoding subtypes of the alpha 2-adrenergic receptor. Identification of a unique receptor subtype. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)99248-3] [Citation(s) in RCA: 169] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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34
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Parker E, Ross E. Truncation of the extended carboxyl-terminal domain increases the expression and regulatory activity of the avian beta-adrenergic receptor. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)92917-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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35
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Hershey AD, Dykema PE, Krause JE. Organization, structure, and expression of the gene encoding the rat substance P receptor. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(20)64331-9] [Citation(s) in RCA: 96] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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36
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Parker EM, Kameyama K, Higashijima T, Ross EM. Reconstitutively active G protein-coupled receptors purified from baculovirus-infected insect cells. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)52467-4] [Citation(s) in RCA: 222] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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37
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38
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The hydrophobic tryptic core of the porcine alpha 2-adrenergic receptor retains allosteric modulation of binding by Na+, H+, and 5-amino-substituted amiloride analogs. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(17)44905-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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39
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A truncation mutation in the avian beta-adrenergic receptor causes agonist-induced internalization and GTP-sensitive agonist binding characteristic of mammalian receptors. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)38261-9] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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40
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Okamoto T, Katada T, Murayama Y, Ui M, Ogata E, Nishimoto I. A simple structure encodes G protein-activating function of the IGF-II/mannose 6-phosphate receptor. Cell 1990; 62:709-17. [PMID: 2167177 DOI: 10.1016/0092-8674(90)90116-v] [Citation(s) in RCA: 239] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The insulin-like growth factor-II/mannose 6-phosphate receptor (IGF-II/man6PR) can directly interact with and activate Gi-2, a GTP binding protein (G protein). We found that the segment of residues 2410-2423 in the human IGF-II/man6PR activates Gi-2 in a manner similar to G-coupled receptors. We observed a hierarchy of the segment action when tested on various G proteins, with an order of Gi-2 greater than Gi-1 approximately Gi-3 greater than Go. The segment had no effect on Gs or low molecular weight G proteins. The segment action depended on its primary structure and was potentiated when the segment was connected with a part of the receptor transmembrane region. Finally, the Gi-2-activating function of the human IGF-II/man6PR could be blocked by an antibody against the segment, indicating a critical role for this small region of the receptor.
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Affiliation(s)
- T Okamoto
- Fourth Department of Internal Medicine, University of Tokyo School of Medicine, Japan
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41
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Chimeric muscarinic cholinergic: beta-adrenergic receptors that activate Gs in response to muscarinic agonists. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)39313-5] [Citation(s) in RCA: 187] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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42
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43
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Raymond JR, Hnatowich M, Lefkowitz RJ, Caron MG. Adrenergic receptors. Models for regulation of signal transduction processes. Hypertension 1990; 15:119-31. [PMID: 2105909 DOI: 10.1161/01.hyp.15.2.119] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Adrenergic receptors are prototypic models for the study of the relations between structure and function of G protein-coupled receptors. Each receptor is encoded by a distinct gene. These receptors are integral membrane proteins with several striking structural features. They consist of a single subunit containing seven stretches of 20-28 hydrophobic amino acids that represent potential membrane-spanning alpha-helixes. Many of these receptors share considerable amino acid sequence homology, particularly in the transmembrane domains. All of these macromolecules share other similarities that include one or more potential sites of extracellular N-linked glycosylation near the amino terminus and several potential sites of regulatory phosphorylation that are located intracellularly. By using a variety of techniques, it has been demonstrated that various regions of the receptor molecules are critical for different receptor functions. The seven transmembrane regions of the receptors appear to form a ligand-binding pocket. Cysteine residues in the extracellular domains may stabilize the ligand-binding pocket by participating in disulfide bonds. The cytoplasmic domains contain regions capable of interacting with G proteins and various kinases and are therefore important in such processes as signal transduction, receptor-G protein coupling, receptor sequestration, and down-regulation. Finally, regions of these macromolecules may undergo posttranslational modifications important in the regulation of receptor function. Our understanding of these complex relations is constantly evolving and much work remains to be done. Greater understanding of the basic mechanisms involved in G protein-coupled, receptor-mediated signal transduction may provide leads into the nature of certain pathophysiological states.
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Affiliation(s)
- J R Raymond
- Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710
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44
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Chapter 11 G Protein-Coupled Receptors: Structure and Function of Signal-Transducing Proteins. ACTA ACUST UNITED AC 1990. [DOI: 10.1016/s0070-2161(08)60173-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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45
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Giros B, Sokoloff P, Martres MP, Riou JF, Emorine LJ, Schwartz JC. Alternative splicing directs the expression of two D2 dopamine receptor isoforms. Nature 1989; 342:923-6. [PMID: 2531847 DOI: 10.1038/342923a0] [Citation(s) in RCA: 501] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Dopamine receptors are classified into D1 and D2 subtypes on the basis of their pharmacological properties and the intracellular responses they mediate. The cerebral D2 dopamine receptor is the target of drugs used to alleviate the main symptoms of schizophrenia. Although it is considered to be a single molecular entity, there is evidence that multiple D2-receptor subtypes exist. A complementary DNA encoding a D2 receptor has recently been cloned and the deduced 415-amino-acid sequence indicates that it belongs to the large superfamily of receptors coupled to G proteins, and that its topology consists of seven transmembrane domains. In this family, the genes are frequently without introns and each is believed to encode a unique polypeptide product. Here we show that the gene for the D2 receptor produces two receptor isoforms by alternative messenger RNA splicing, providing a route to receptor diversity in this family. One isoform corresponds to the D2(415) receptor, but the second contains an additional sequence encoding a 29-amino-acid fragment, defining a novel D2(444) receptor isoform. Expression of the two isoforms is tissue-specific, and both are regulated by guanyl nucleotides. As the extra sequence is located within a putative cytoplasmic loop that binds to G proteins, the two isoforms might interact with different G proteins and thereby initiate distinct intracellular signals.
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Affiliation(s)
- B Giros
- Unité de Neurobiologie et Pharmacologie, U. 109 de l'inserm Centre Paul Broca, Paris, France
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46
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Dunkel FG, Münch G, Boege F, Cantrill R, Kurstjens NP. Proteolytic degradation routes for turkey beta 1-adrenoceptor probed with antipeptide antibodies against the N-terminal sequence of the receptor. Biochem Biophys Res Commun 1989; 165:264-70. [PMID: 2556137 DOI: 10.1016/0006-291x(89)91064-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Anti-peptide antibodies, raised against the N-terminal sequence (amino acids 2-10) of the turkey beta 1-adrenoceptor [Yarden et al., Proc. Natl. Acad. Sci. USA (1986) 83, 6795-6799] recognized the 50 kDa- but not the 40 kDa-form of the receptor, thus confirming the previous assumption that the N-terminus of the 50 kDa form is lost during its conversion to the 40 kDa-form [Jür beta, R., Hekman, M. & Helmreich, E.J.M. (1985) Biochemistry 24, 3349-3354]. By in situ proteolysis small amounts of receptor fragments were formed, which could be recognized by the N-terminus specific antibody. Therefore, although the production of the stable 40 kDa receptor species by proteolytic removal of a portion of the N-terminal appears to be the predominant route, there exists an additional pathway of degradation which must involve the initial cleavage of the carboxyl terminal.
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Affiliation(s)
- F G Dunkel
- Department of Physiological Chemistry, University of Würzburg, Medical School, Federal Republic of Germany
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Affiliation(s)
- E M Ross
- Department of Pharmacology, Southwestern Graduate School of Biomedical Sciences, University of Texas Southwestern Medical Center, Dallas 75235-9041
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48
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Wang H, Lipfert L, Malbon CC, Bahouth S. Site-directed Anti-peptide Antibodies Define the Topography of the β-Adrenergic Receptor. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)71696-7] [Citation(s) in RCA: 100] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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49
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Parini A, Coupry I, Graham RM, Uzielli I, Atlas D, Lanier SM. Characterization of an imidazoline/guanidinium receptive site distinct from the α2-adrenergic receptor. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)80147-8] [Citation(s) in RCA: 96] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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50
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Abstract
The nicotinic (nAcChR) and muscarinic (mAcCh) acetylcholine receptors and acetylcholinesterase (AcChEase) are structurally unrelated but share a common functional property: interaction with acetylcholine (AcCh). Alignment of the probable AcCh binding site regions of the nAcChR and mAcChR protein sequences revealed the presence of ten nearly identically spaced consensus residues, six of which contain potentially ligand-interactive side chains. Important elements of the consensus residues also were found in one unique sequence region of the AcChEases. Alignments among the two receptors and AcChEase outside the apparent binding region were rare, and the consensus AcCh binding residues were largely substituted in the homologous proteins, which do not bind AcCh. The consensus residues include two possible anionic subsite Asp residues and a Ser that may hydrogen bond to the AcCh carbonyl in the receptors. These residues correspond to positions Asp-166, Ser-173, and Asp-200 in the neuromuscular nAcChR; Asp-71, Ser-78, and Asp-105 in the M1 mAcChR; and Asp-93 and Asp-128 in Torpedo AcChEase. No corresponding consensus Ser is found in the AcChEase sequence; this is expected because of a downstream esterase active-site Ser-200 (Torpedo). A receptor-conserved and disulfide-linked Cys corresponding to neuromuscular nAcChR residue 193 and M1 mAcChR residue 97 may be important in energy transduction associated with agonist-mediated events. The presence of additional binding-site aromatic residues that may form a hydrophobic environment near the anionic subsite are aligned within, but not between, the three cholinergic protein groups. These observations target specific regions and residues within these proteins for structure-function studies of the cholinergic binding domain.
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Affiliation(s)
- G L Peterson
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis 97331
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