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Zhang H, Chu G, Wang G, Yao M, Lu S, Chen T. Mechanistic Understanding of the Palmitoylation of G o Protein in the Allosteric Regulation of Adhesion Receptor GPR97. Pharmaceutics 2022; 14:pharmaceutics14091856. [PMID: 36145604 PMCID: PMC9504338 DOI: 10.3390/pharmaceutics14091856] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 08/24/2022] [Accepted: 08/30/2022] [Indexed: 11/21/2022] Open
Abstract
Adhesion G-protein-coupled receptors (aGPCRs)—a major family of GPCRs—play critical roles in the regulation of tissue development and cancer progression. The orphan receptor GPR97, activated by glucocorticoid stress hormones, is a prototypical aGPCR. Although it has been established that the palmitoylation of the C-terminal Go protein is essential for Go’s efficient engagement with the active GPR97, the detailed allosteric mechanism remains to be clarified. Hence, we performed extensive large-scale molecular dynamics (MD) simulations of the GPR97−Go complex in the presence or absence of Go palmitoylation. The conformational landscapes analyzed by Markov state models revealed that the overall conformation of GPR97 is preferred to be fully active when interacting with palmitoylated Go protein. Structural and energetic analyses indicated that the palmitoylation of Go can allosterically stabilize the critical residues in the ligand-binding pocket of GPR97 and increase the affinity of the ligand for GPR97. Furthermore, the community network analysis suggests that the palmitoylation of Go not only allosterically strengthens the internal interactions between Gαo and Gβγ, but also enhances the coupling between Go and GPR97. Our study provides mechanistic insights into the regulation of aGPCRs via post-translational modifications of the Go protein, and offers guidance for future drug design of aGPCRs.
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Affiliation(s)
- Hao Zhang
- Department of Plastic and Reconstructive Surgery, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai 200011, China
| | - Guojun Chu
- Department of Cardiology, Changzheng Hospital, Naval Medical University, Shanghai 200003, China
| | - Gaoming Wang
- Medicinal Chemistry and Bioinformatics Center, Shanghai Jiao Tong University, School of Medicine, Shanghai 200025, China
| | - Min Yao
- Department of Plastic and Reconstructive Surgery, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai 200011, China
- Correspondence: (M.Y.); (S.L.); (T.C.)
| | - Shaoyong Lu
- Medicinal Chemistry and Bioinformatics Center, Shanghai Jiao Tong University, School of Medicine, Shanghai 200025, China
- Correspondence: (M.Y.); (S.L.); (T.C.)
| | - Ting Chen
- Department of Cardiology, Changzheng Hospital, Naval Medical University, Shanghai 200003, China
- Correspondence: (M.Y.); (S.L.); (T.C.)
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de Grip WJ, Ganapathy S. Rhodopsins: An Excitingly Versatile Protein Species for Research, Development and Creative Engineering. Front Chem 2022; 10:879609. [PMID: 35815212 PMCID: PMC9257189 DOI: 10.3389/fchem.2022.879609] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Accepted: 05/16/2022] [Indexed: 01/17/2023] Open
Abstract
The first member and eponym of the rhodopsin family was identified in the 1930s as the visual pigment of the rod photoreceptor cell in the animal retina. It was found to be a membrane protein, owing its photosensitivity to the presence of a covalently bound chromophoric group. This group, derived from vitamin A, was appropriately dubbed retinal. In the 1970s a microbial counterpart of this species was discovered in an archaeon, being a membrane protein also harbouring retinal as a chromophore, and named bacteriorhodopsin. Since their discovery a photogenic panorama unfolded, where up to date new members and subspecies with a variety of light-driven functionality have been added to this family. The animal branch, meanwhile categorized as type-2 rhodopsins, turned out to form a large subclass in the superfamily of G protein-coupled receptors and are essential to multiple elements of light-dependent animal sensory physiology. The microbial branch, the type-1 rhodopsins, largely function as light-driven ion pumps or channels, but also contain sensory-active and enzyme-sustaining subspecies. In this review we will follow the development of this exciting membrane protein panorama in a representative number of highlights and will present a prospect of their extraordinary future potential.
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Affiliation(s)
- Willem J. de Grip
- Leiden Institute of Chemistry, Department of Biophysical Organic Chemistry, Leiden University, Leiden, Netherlands
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - Srividya Ganapathy
- Department of Imaging Physics, Delft University of Technology, Netherlands
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Cuozzo JW, Soutter HH. Overview of Recent Progress in Protein-Expression Technologies for Small-Molecule Screening. ACTA ACUST UNITED AC 2014; 19:1000-13. [PMID: 24525871 DOI: 10.1177/1087057114520975] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 01/02/2014] [Indexed: 01/09/2023]
Abstract
Production of novel soluble and membrane-localized protein targets for functional and affinity-based screening has often been limited by the inability of traditional protein-expression systems to generate recombinant proteins that have properties similar to those of their endogenous counterparts. Such targets have often been labeled as challenging. Although biological validation of these challenging targets for specific disease areas may be strong, discovery of small-molecule modulators can be greatly delayed or completely halted due to target-expression issues. In this article, the limitations of traditional protein-expression systems will be discussed along with new systems designed to overcome these challenges. Recent work in this field has focused on two major areas for both soluble and membrane targets: construct-design strategies to improve expression levels and new hosts that can carry out the posttranslational modifications necessary for proper target folding and function. Another area of active research has been on the reconstitution of solubilized membrane targets for both structural analysis and screening. Finally, the potential impact of these new systems on the output of small-molecule screening campaigns will be discussed.
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Sikarwar AS, Hinton M, Santhosh KT, Chelikani P, Dakshinamurti S. Palmitoylation of Gαq Determines its Association with the Thromboxane Receptor in Hypoxic Pulmonary Hypertension. Am J Respir Cell Mol Biol 2013; 50:135-43. [DOI: 10.1165/rcmb.2013-0085oc] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Guan X, Fierke CA. Understanding Protein Palmitoylation: Biological Significance and Enzymology. Sci China Chem 2011; 54:1888-1897. [PMID: 25419213 DOI: 10.1007/s11426-011-4428-2] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Protein palmitoylation is a widespread lipid modification in which one or more cysteine thiols on a substrate protein are modified to form a thioester with a palmitoyl group. This lipid modification is readily reversible; a feature of protein palmitoylation that allows for rapid regulation of the function of many cellular proteins. Mutations in palmitoyltransferases (PATs), the enzymes that catalyze the formation of this modification, are associated with a number of neurological diseases and cancer progression. This review summarizes the crucial role of palmitoylation in biological systems, the discovery of the DHHC protein family that catalyzes protein palmitoylation, and the development of methods for investigating the catalytic mechanism of PATs.
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Affiliation(s)
- Xiaomu Guan
- Departments of Chemistry and Biological Chemistry, University of Michigan, 930 N University, Ann Arbor, MI 48109-1055, USA
| | - Carol A Fierke
- Departments of Chemistry and Biological Chemistry, University of Michigan, 930 N University, Ann Arbor, MI 48109-1055, USA
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Abstract
This chapter will review the basic pharmacology of endocannabinoid receptors. As the best-described cannabinoid receptors are G-protein-coupled receptors (GPCRs), those will be the focus of this chapter. We will start with a basic review of GPCR signaling, as these concepts are critical to understanding the function of cannabinoid receptors. Next, several features of cannabinoid receptor signaling will be presented, with an emphasis on the effectors modulated by cannabinoid receptors. Finally, we will finish with a discussion of cannabinoid receptor agonists and antagonists and future directions. The aim of this chapter is to introduce the cannabinoid receptor pharmacology that will be necessary to appreciate the intricacies of endocannabinoid signaling presented in later chapters.
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Case R, Sharp E, Benned-Jensen T, Rosenkilde MM, Davis-Poynter N, Farrell HE. Functional analysis of the murine cytomegalovirus chemokine receptor homologue M33: ablation of constitutive signaling is associated with an attenuated phenotype in vivo. J Virol 2008; 82:1884-98. [PMID: 18057236 PMCID: PMC2258698 DOI: 10.1128/jvi.02550-06] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2006] [Accepted: 11/20/2007] [Indexed: 01/28/2023] Open
Abstract
The murine cytomegalovirus (MCMV) M33 gene is conserved among all betaherpesviruses and encodes a homologue of seven-transmembrane receptors (7TMR) with the capacity for constitutive signaling. Previous studies have demonstrated that M33 is important for MCMV dissemination to or replication within the salivary glands. In this study, we probed N- and C-terminal regions of M33 as well as known 7TMR signature motifs in transmembrane (TM) II and TM III to determine the impact on cell surface expression, constitutive signaling, and in vivo phenotype. The region between amino acids R(340) and A(353) of the C terminus was found to be important for CREB- and NFAT-mediated signaling, although not essential for phosphatidylinositol turnover. Tagging or truncation of the N terminus of M33 resulted in loss of cell surface expression. Within TM II, an F79D mutation abolished constitutive signaling, demonstrating a role, as in other cellular and viral 7TMR, of TM II in receptor activation. In TM III, the arginine (but not the asparagine) residue of the NRY motif (the counterpart of the common DRY motif in cellular 7TMR) was found to be essential for constitutive signaling. Selected mutations incorporated into recombinant MCMV showed that disruption of constitutive signaling for a viral 7TMR homologue resulted in a reduced capacity to disseminate to or replicate in the salivary glands. In addition, HCMV UL33 was found to partially compensate for the lack of M33 in vivo, suggesting conserved biological roles of the UL33 gene family.
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Affiliation(s)
- Ruth Case
- Clinical Medical Virology Centre, University of Queensland, Sir Albert Sakzewski Virus Research Centre, Royal Children's Hospital, Herston 4029, Queensland, Australia
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Migrenne S, Magnan C, Cruciani-Guglielmacci C. Fatty acid sensing and nervous control of energy homeostasis. DIABETES & METABOLISM 2007; 33:177-82. [PMID: 17475532 DOI: 10.1016/j.diabet.2007.01.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2007] [Accepted: 01/28/2007] [Indexed: 10/23/2022]
Abstract
Nutrient sensitive neurons (glucose and fatty acids, FA) are present in both the hypothalamus and the brainstem and play a key role in nervous control of energy homeostasis. Through neuronal output, especially the autonomic nervous system, it is now evidenced that FA may modulate food behaviour and both insulin secretion and action. For example, central administration of oleate inhibits both food intake and hepatic glucose production in rats. This suggests that a slight increase in plasma FA concentrations in the postprandial state might be detected by the central nervous system as a satiety signal. At cellular levels, subpopulations of FA-sensitive neurons (either excited or inhibited by FA) are now identified within the hypothalamus. However molecular effectors of FA effects remain unclear. They probably include ionic channels such as chloride or potassium. FA metabolism seems also required to induce neuronal response. Thus, FA per se or their metabolites modulate neuronal activity, as a mean of directly monitoring ongoing fuel availability by CNS nutrient-sensing neurons involved in the regulation of insulin secretion. Beside these physiological effects, FA overload or dysfunction of their metabolism could impair nervous control of energy homeostasis and contribute to development of obesity and/or type 2 diabetes in predisposed subjects.
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Affiliation(s)
- S Migrenne
- Université Paris-VII, CNRS UMR 7059, 2, place Jussieu, PO Box 7126, 75251 Paris cedex 5, France
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10
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Muccioli G, Baragli A, Granata R, Papotti M, Ghigo E. Heterogeneity of ghrelin/growth hormone secretagogue receptors. Toward the understanding of the molecular identity of novel ghrelin/GHS receptors. Neuroendocrinology 2007; 86:147-64. [PMID: 17622734 DOI: 10.1159/000105141] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2007] [Accepted: 05/21/2007] [Indexed: 12/23/2022]
Abstract
Ghrelin is a gastric polypeptide displaying strong GH-releasing activity by activation of the type 1a GH secretagogue receptor (GHS-R1a) located in the hypothalamus-pituitary axis. GHS-R1a is a G-protein-coupled receptor that, upon the binding of ghrelin or synthetic peptidyl and non-peptidyl ghrelin-mimetic agents known as GHS, preferentially couples to G(q), ultimately leading to increased intracellular calcium content. Beside the potent GH-releasing action, ghrelin and GHS influence food intake, gut motility, sleep, memory and behavior, glucose and lipid metabolism, cardiovascular performances, cell proliferation, immunological responses and reproduction. A growing body of evidence suggests that the cloned GHS-R1a alone cannot be the responsible for all these effects. The cloned GHS-R1b splice variant is apparently non-ghrelin/GHS-responsive, despite demonstration of expression in neoplastic tissues responsive to ghrelin not expressing GHS-R1a; GHS-R1a homologues sensitive to ghrelin are capable of interaction with GHS-R1b, forming heterodimeric species. Furthermore, GHS-R1a-deficient mice do not show evident abnormalities in growth and diet-induced obesity, suggesting the involvement of another receptor. Additional evidence of the existence of another receptor is that ghrelin and GHS do not always share the same biological activities and activate a variety of intracellular signalling systems besides G(q). The biological actions on the heart, adipose tissue, pancreas, cancer cells and brain shared by ghrelin and the non-acylated form of ghrelin (des-octanoyl ghrelin), which does not bind GHS-R1a, represent the best evidence for the existence of a still unknown, functionally active binding site for this family of molecules. Finally, located in the heart and blood vessels is the scavenger receptor CD36, involved in the endocytosis of the pro-atherogenic oxidized low-density lipoproteins, which is a pharmacologically and structurally distinct receptor for peptidyl GHS and not for ghrelin. This review highlights the most recently discovered features of GHS-R1a and the emerging evidence for a novel group of receptors that are not of the GHS1a type; these appear involved in the transduction of the multiple levels of information provided by GHS and ghrelin.
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Affiliation(s)
- Giampiero Muccioli
- Division of Pharmacology, Department of Anatomy, Pharmacology and Forensic Medicine, University of Turin, Turin, Italy
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11
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Protein Prenylation: An (Almost) Comprehensive Overview on Discovery History, Enzymology, and Significance in Physiology and Disease. MONATSHEFTE FUR CHEMIE 2006. [DOI: 10.1007/s00706-006-0534-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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12
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Xue L, Gollapalli DR, Maiti P, Jahng WJ, Rando RR. A Palmitoylation Switch Mechanism in the Regulation of the Visual Cycle. Cell 2004; 117:761-71. [PMID: 15186777 DOI: 10.1016/j.cell.2004.05.016] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2004] [Revised: 04/09/2004] [Accepted: 04/20/2004] [Indexed: 12/01/2022]
Abstract
RPE65 is essential for the biosynthesis of 11-cis-retinal, the chromophore of rhodopsin. Here, we show that the membrane-associated form (mRPE65) is triply palmitoylated and is a chaperone for all-trans-retinyl esters, allowing their entry into the visual cycle for processing into 11-cis-retinal. The soluble form of RPE65 (sRPE65) is not palmitoylated and is a chaperone for vitamin A, rather than all-trans-retinyl esters. Thus, the palmitoylation of RPE65 controls its ligand binding selectivity. The two chaperones are interconverted by lecithin retinol acyl transferase (LRAT) acting as a molecular switch. Here mRPE65 is a palmitoyl donor, revealing a new acyl carrier protein role for palmitoylated proteins. When chromophore synthesis is not required, mRPE65 is converted into sRPE65 by LRAT, and further chromophore synthesis is blocked. The studies reveal new roles for palmitoylated proteins as molecular switches and LRAT as a palmitoyl transferase whose role is to catalyze the mRPE65 to sRPE65 conversion.
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Affiliation(s)
- Linlong Xue
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 45 Shattuck Street, Boston, MA 02115, USA
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13
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Feng GJ, Kellett E, Scorer CA, Wilde J, White JH, Milligan G. Selective interactions between helix VIII of the human mu-opioid receptors and the C terminus of periplakin disrupt G protein activation. J Biol Chem 2003; 278:33400-7. [PMID: 12810704 DOI: 10.1074/jbc.m305866200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Analysis of interactions between the C-terminal tail of the MOP-1 and MOP-1A variants of the human mu-opioid receptor with proteins derived from a human brain cDNA library resulted in identification of the actin and intermediate filament-binding protein periplakin. Mapping of this interaction indicated that the predicted fourth intracellular loop/helix VIII of the receptor interacts with the C-terminal rod and linker region of periplakin. Periplakin is widely expressed in the central nervous system of both man and rat and demonstrated an overlapping but not identical distribution with mu-opioid (MOP) receptors. Co-expression of periplakin with MOP-1 or a MOP-1-eYFP fusion construct in HEK293 cells did not interfere with agonist-mediated internalization of the receptor. When co-expressed with a MOP-1-Gi1 alpha fusion protein periplakin significantly reduced the capacity of the agonist to stimulate binding of 35S-labeled guanosine 5'-3-O-(thio)triphosphate ([35S]GTP gamma S) to the receptor-associated G protein. By contrast, periplakin did not interfere with agonist-stimulation of [35S]GTP gamma S binding to either an alpha 2A-adrenoreceptor-Gi1 alpha fusion protein or a beta2-adrenoreceptor-Gs alpha fusion protein, indicating its selectivity of function. This represents the first example of an opioid receptor-interacting protein that functions to disrupt agonist-mediated G protein activation.
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MESH Headings
- Actins/chemistry
- Amino Acid Sequence
- Biotin/pharmacology
- Brain/metabolism
- Cell Line
- Cell Membrane/metabolism
- Central Nervous System/metabolism
- Cytoskeletal Proteins/chemistry
- DNA/metabolism
- DNA, Complementary/metabolism
- GTP-Binding Proteins/metabolism
- Gene Library
- Glutathione Transferase/metabolism
- Guanosine 5'-O-(3-Thiotriphosphate)/metabolism
- Histidine/chemistry
- Humans
- Immunoblotting
- Ligands
- Microscopy, Confocal
- Microscopy, Fluorescence
- Molecular Sequence Data
- Plakins
- Protein Binding
- Protein Isoforms
- Protein Structure, Tertiary
- RNA, Messenger/metabolism
- Receptors, Opioid, mu/chemistry
- Receptors, Opioid, mu/metabolism
- Recombinant Fusion Proteins/metabolism
- Sequence Homology, Amino Acid
- Tissue Distribution
- Transfection
- Two-Hybrid System Techniques
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Affiliation(s)
- Giu-Jie Feng
- Molecular Pharmacology Group, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
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14
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Maurer-Stroh S, Washietl S, Eisenhaber F. Protein prenyltransferases: anchor size, pseudogenes and parasites. Biol Chem 2003; 384:977-89. [PMID: 12956414 DOI: 10.1515/bc.2003.110] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Lipid modification of eukaryotic proteins by protein prenyltransferases is required for critical signaling pathways, cell cycle progression, cytoskeleton remodeling, induction of apoptosis and vesicular trafficking. This review analyzes the influence of distinct states of sequential posttranslational processing that can be obtained after single or double prenylation, reversible palmitoylation, proteolytic cleavage of the C-terminus and possible reversible carboxymethylation. This series of modifications, as well as the exact length of the prenyl anchor, are determinants in protein-membrane and specific protein-protein interactions of protein prenyltransferase substrates. Furthermore, the occurrence and distribution of pseudogenes of protein prenyltransferase subunits are discussed. Besides being developed as anti-cancer agents, prenyltransferase inhibitors are effective against an increasing number of parasitic diseases. Extensive screens for protein prenyltransferases in genomic data of fungal and protozoan pathogens unveil a series of new pharmacologic targets for prenyltransferase inhibition, including the parasites Brugia malayi, Onchocerca volvulus, Aspergillus nidulans, Pneumocystis carinii, Entamoeba histolytica, Strongyloides stercoralis, Trichinella spiralis and Cryptosporidium parvum.
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15
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Wyse BD, Prior IA, Qian H, Morrow IC, Nixon S, Muncke C, Kurzchalia TV, Thomas WG, Parton RG, Hancock JF. Caveolin interacts with the angiotensin II type 1 receptor during exocytic transport but not at the plasma membrane. J Biol Chem 2003; 278:23738-46. [PMID: 12692121 DOI: 10.1074/jbc.m212892200] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mechanisms involved in angiotensin II type 1 receptor (AT1-R) trafficking and membrane localization are largely unknown. In this study, we examined the role of caveolin in these processes. Electron microscopy of plasma membrane sheets shows that the AT1-R is not concentrated in caveolae but is clustered in cholesterol-independent microdomains; upon activation, it partially redistributes to lipid rafts. Despite the lack of AT1-R in caveolae, AT1-R.caveolin complexes are readily detectable in cells co-expressing both proteins. This interaction requires an intact caveolin scaffolding domain because mutant caveolins that lack a functional caveolin scaffolding domain do not interact with AT1-R. Expression of an N-terminally truncated caveolin-3, CavDGV, that localizes to lipid bodies, or a point mutant, Cav3-P104L, that accumulates in the Golgi mislocalizes AT1-R to lipid bodies and Golgi, respectively. Mislocalization results in aberrant maturation and surface expression of AT1-R, effects that are not reversed by supplementing cells with cholesterol. Similarly mutation of aromatic residues in the caveolin-binding site abrogates AT1-R cell surface expression. In cells lacking caveolin-1 or caveolin-3, AT1-R does not traffic to the cell surface unless caveolin is ectopically expressed. This observation is recapitulated in caveolin-1 null mice that have a 55% reduction in renal AT1-R levels compared with controls. Taken together our results indicate that a direct interaction with caveolin is required to traffic the AT1-R through the exocytic pathway, but this does not result in AT1-R sequestration in caveolae. Caveolin therefore acts as a molecular chaperone rather than a plasma membrane scaffold for AT1-R.
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Affiliation(s)
- Bruce D Wyse
- Department of Molecular and Cellular Pathology, University of Queensland, Brisbane, Queensland, Australia
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16
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Logan DW, Bryson-Richardson RJ, Taylor MS, Currie P, Jackson IJ. Sequence characterization of teleost fish melanocortin receptors. Ann N Y Acad Sci 2003; 994:319-30. [PMID: 12851332 DOI: 10.1111/j.1749-6632.2003.tb03196.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Zebrafish are an excellent model system for studying the function of melanocortins in developmental and physiological processes, not least because there are a considerable number of mutant lines in which pigment patterns are affected. The behavior of fish melanophores is influenced by alpha-melanocyte-stimulating hormone (alpha-MSH) and melanin-concentrating hormone (MCH). We have used a rapid assay for alpha-MSH and MCH function using melanophores present on single zebrafish scales. By in silico analysis, we have identified the full complement of melanocortin receptors in both zebrafish and the pufferfish, FUGU: Mammals have five such receptors. Zebrafish have six melanocortin receptors, including two MC5R orthologues, whereas Fugu, lacking MC3R, has only four. We have confirmed the sequences of these 10 genes and show the comparison of the amino acid sequences of the encoded proteins with the orthologous receptor in other vertebrates.
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Affiliation(s)
- Darren W Logan
- MRC Human Genetics Unit, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, United Kingdom
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17
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Miggin SM, Lawler OA, Kinsella BT. Palmitoylation of the human prostacyclin receptor. Functional implications of palmitoylation and isoprenylation. J Biol Chem 2003; 278:6947-58. [PMID: 12488443 DOI: 10.1074/jbc.m210637200] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have previously established that isoprenylation of the prostacyclin receptor (IP) is required for its efficient G protein coupling and effector signaling (Hayes, J. S., Lawler, O. A., Walsh, M. T., and Kinsella, B. T. (1999) J. Biol. Chem. 274, 23707-23718). In the present study, we sought to investigate whether the IP may actually be subject to palmitoylation in addition to isoprenylation and to establish the functional significance thereof. The human (h) IP was efficiently palmitoylated at Cys(308) and Cys(311), proximal to transmembrane domain 7 within its carboxyl-terminal (C)-tail domain, whereas Cys(309) was not palmitoylated. The isoprenylation-defective hIP(SSLC) underwent palmitoylation but did not efficiently couple to G(s) or G(q), confirming that isoprenylation is required for G protein coupling. Deletion of C-tail sequences distal to Val(307) generated hIP(Delta307) that was neither palmitoylated nor isoprenylated and did not efficiently couple to G(s) or to G(q), whereas hIP(Delta312) was palmitoylated and ably coupled to both effector systems. Conversion of Cys(308), Cys(309), Cys(311), Cys(308,309), or Cys(309,311) to corresponding Ser residues, while leaving the isoprenylation CAAX motif intact, did not affect hIP coupling to G(s) signaling, whereas mutation of Cys(308,311) and Cys(308,309,311) abolished signaling, indicating that palmitoylation of either Cys(308) or Cys(311) is sufficient to maintain functional G(s) coupling. Although mutation of Cys(309) and Cys(311) did not affect hIP-mediated G(q) coupling, mutation of Cys(308) abolished signaling, indicating a specific requirement for palmitoylation of Cys(308) for G(q) coupling. Consistent with this, neither hIP(C308S,C309S), hIP(C308S,C311S), nor hIP(C308S,C309S,C311S) coupled to G(q). Taken together, these data confirm that the hIP is isoprenylated and palmitoylated, and collectively these modifications modulate its G protein coupling and effector signaling. We propose that through lipid modification followed by membrane insertion, the C-tail domain of the IP may contain a double loop structure anchored by the dynamically regulated palmitoyl groups proximal to transmembrane domain 7 and by a distal farnesyl isoprenoid permanently attached to its carboxyl terminus.
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Affiliation(s)
- Sinead M Miggin
- Department of Biochemistry, Conway Institute of Biomolecular and Biomedical Research, Merville House, University College Dublin, Belfield, Dublin 4, Ireland
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18
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Abstract
SUMMARY Three different protein prenyltransferases (farnesyltransferase and geranylgeranyltransferases I and II) catalyze the attachment of prenyl lipid anchors 15 or 20 carbons long to the carboxyl termini of a variety of eukaryotic proteins. Farnesyltransferase and geranylgeranyltransferase I both recognize a 'Ca1a2X' motif on their protein substrates; geranylgeranyltransferase II recognizes a different, non-CaaX motif. Each enzyme has two subunits. The genes encoding CaaX protein prenyltransferases are considerably longer than those encoding non-CaaX subunits, as a result of longer introns. Alternative splice forms are predicted to occur, but the extent to which each splice form is translated and the functions of the different resulting isoforms remain to be established. Farnesyltransferase-inhibitor drugs have been developed as anti-cancer agents and may also be able to treat several other diseases. The effects of these inhibitors are complicated, however, by the overlapping substrate specificities of geranylgeranyltransferase I and farnesyltransferase.
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Qanbar R, Bouvier M. Role of palmitoylation/depalmitoylation reactions in G-protein-coupled receptor function. Pharmacol Ther 2003; 97:1-33. [PMID: 12493533 DOI: 10.1016/s0163-7258(02)00300-5] [Citation(s) in RCA: 189] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
G-protein-coupled receptors (GPCRs) constitute one of the largest protein families in the human genome. They are subject to numerous post-translational modifications, including palmitoylation. This review highlights the dynamic nature of palmitoylation and its role in GPCR expression and function. The palmitoylation of other proteins involved in GPCR signaling, such as G-proteins, regulators of G-protein signaling, and G-protein-coupled receptor kinases, is also discussed.
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Affiliation(s)
- Riad Qanbar
- Département de Biochimie, Université de Montréal, C.P. 6128 Succursale Centre-Ville, 2900 Edouard Montpetit, Montreál, Quebec, Canada H3C 3J7
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20
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Yik JHN, Weigel PH. The position of cysteine relative to the transmembrane domain is critical for palmitoylation of H1, the major subunit of the human asialoglycoprotein receptor. J Biol Chem 2002; 277:47305-12. [PMID: 12370180 DOI: 10.1074/jbc.m208751200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mammalian hepatic asialoglycoprotein receptor (ASGP-R) is an endocytic recycling receptor that mediates the internalization of desialylated glycoproteins and their delivery to lysosomes where they are degraded. The human ASGP-R is a hetero-oligomeric complex composed of two subunits designated H1 and H2. Both subunits are palmitoylated at the cytoplasmic Cys residues near their transmembrane domains (TMD). The cytoplasmic Cys(36) in H1 is located at a position that is five amino acids from the transmembrane junction. Because the sequences of subunits in all mammalian ASGP-R species are highly conserved especially at the region near the palmitoylated Cys, we sought to identify a recognition signal for the palmitoylation of H1. Various types of H1 mutants were created by site-directed or deletion mutagenesis including alteration of the amino acids surrounding Cys(36), replacing portions of the TMD with that of a different protein and partial deletion of the cytoplasmic domain as well as transposing the palmitoylated Cys to positions further away from the TMD. Mutant H1 cDNAs were transiently expressed in COS-7 cells, and the H1 proteins were analyzed after metabolic labeling with [(3)H]palmitate. The results indicate that neither the native amino acid sequence surrounding Cys(36) nor the majority of the cytoplasmic domain sequence is critical for palmitoylation. Palmitoylation was also not dependent on the native TMD of H1. In contrast, the attachment of palmitate was abolished if the Cys residue was transposed to a position that was 30 amino acids away from the transmembrane border. We conclude that the spacing of a Cys residue relative to the TMD in the primary protein sequence of H1 is the major determinant for successful palmitoylation.
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Affiliation(s)
- Jasper H N Yik
- Department of Biochemistry & Molecular Biology and the Oklahoma Center for Medical Glycobiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73190, USA
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21
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Yik JHN, Saxena A, Weigel JA, Weigel PH. Nonpalmitoylated human asialoglycoprotein receptors recycle constitutively but are defective in coated pit-mediated endocytosis, dissociation, and delivery of ligand to lysosomes. J Biol Chem 2002; 277:40844-52. [PMID: 12171918 DOI: 10.1074/jbc.m204780200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The hepatic asialoglycoprotein receptor (ASGP-R) internalizes desialylated glycoproteins via the clathrin-coated pit pathway and mediates their delivery to lysosomes for degradation. The human ASGP-R contains two subunits, H1 and H2. Cytoplasmic residues Cys(36) in H1, as well as Cys(54) and Cys(58) in H2 are palmitoylated (Zeng, F.-Y., and Weigel, P. H. (1996) J. Biol. Chem. 271, 32454). In order to study the function(s) of ASGP-R palmitoylation, we mutated these Cys residues to Ser and generated stably transfected SK-Hep-1 cell lines expressing either wild-type or nonpalmitoylated ASGP-Rs. Compared with wild-type ASGP-Rs, palmitoylation-defective ASGP-Rs showed normal ligand binding, intracellular distribution and trafficking patterns, and pH-induced dissociation profiles in vitro. However, continuous ASOR uptake, and the uptake of prebound cell surface ASOR were slower in cells expressing palmitoylation-defective ASGP-Rs than in cells expressing wild-type ASGP-Rs. Unlike native ASGP-Rs in hepatocytes or hepatoma cells, which mediate endocytosis via the clathrin-coated pit pathway and are almost completely inhibited by hypertonic medium, only approximately 40% of the ASOR uptake in SK-Hep-1 cells expressing wild-type ASGP-Rs was inhibited by hyperosmolarity. This result suggests the existence of an alternate nonclathrin-mediated internalization pathway, such as transcytosis, for the entry of ASGP-R.ASOR complexes into these cells. In contrast, ASOR uptake mediated by cells expressing palmitoylation-defective ASGP-Rs showed only a marginal difference under hypertonic conditions, indicating that most of the nonpalmitoylated ASGP-Rs were not internalized and processed normally through the clathrin-coated pit pathway. Furthermore, cells expressing wild-type ASGP-Rs were able to degrade the internalized ASOR, whereas ASOR dissociation was impaired and degradation was barely detectable in cells expressing nonpalmitoylated ASGP-Rs. We conclude that palmitoylation of the ASGP-R is required for its efficient endocytosis of ligand by the clathrin-dependent endocytic pathway and, in particular, for the proper dissociation and delivery of ligand to lysosomes.
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Affiliation(s)
- Jasper H N Yik
- Department of Biochemistry & Molecular Biology, The Oklahoma Center for Medical Glycobiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73190, USA
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22
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Yik JHN, Saxena A, Weigel JA, Weigel PH. Palmitoylation-defective asialoglycoprotein receptors are normal in their cellular distribution and ability to bind ligand, but are defective in ligand uptake and degradation. Biochem Biophys Res Commun 2002; 297:980-6. [PMID: 12359251 DOI: 10.1016/s0006-291x(02)02298-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The hepatic asialoglycoprotein receptor (ASGP-R) is an endocytic recycling receptor that mediates the endocytosis of desialylated glycoproteins. The human ASGP-R is composed of two homologous subunits, H1 and H2, and the cytoplasmic Cys residues in both subunits are palmitoylated. To study the effects of palmitoylation on ASGP-R activity and function, we generated four types of stably transfected cell lines in SK-Hep-1 hepatoma cells, expressing wild-type, or partially or completely palmitoylation-defective ASGP-Rs containing Cys-to-Ser mutations in either one or both subunits. Scatchard analysis showed that all four stable cell lines expressed a similar number of binding sites for asialo-orosomucoid, with comparable dissociation constants of approximately 1-3nM. Immunofluorescence confocal microscopy indicated a normal distribution of the palmitoylation-defective H1 and H2 subunits compared to the wild-type. However, cell lines expressing palmitoylation-defective ASGP-Rs had markedly reduced rates of ligand uptake and degradation compared to cells expressing wild-type ASGP-Rs. We conclude that failure to palmitoylate Cys residues in either or both subunits of human ASGP-Rs results in very inefficient uptake and degradation of ligands.
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Affiliation(s)
- Jasper H N Yik
- Department of Biochemistry and Molecular Biology, Oklahoma Center for Medical Glycobiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73190, USA
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23
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Duncan JA, Gilman AG. Characterization of Saccharomyces cerevisiae acyl-protein thioesterase 1, the enzyme responsible for G protein alpha subunit deacylation in vivo. J Biol Chem 2002; 277:31740-52. [PMID: 12080046 DOI: 10.1074/jbc.m202505200] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Thioacylation is a reversible lipid modification of proteins that plays a role in the regulation of signal transduction. Acyl-protein thioesterase 1 (APT1) was identified as an enzyme capable of deacylating some thioacylated proteins in vitro. Saccharomyces cerevisiae open reading frame YLR118c encodes an enzyme homologous to Rattus norvegicus APT1. We demonstrate that the catalytic activity of the protein encoded by the yeast open reading frame is similar to that of rat APT1, and we designate the protein S. cerevisiae Apt1p. Yeasts bearing a disruption of the APT1 gene lack significant biochemically detectable acyl-protein thioesterase activity. They also fail to deacylate Gpa1p, the yeast G alpha subunit, in metabolic radiolabeling studies. We conclude that native APT1 is the enzyme responsible for G alpha subunit deacylation in S. cerevisiae and presumably other eukaryotes as well.
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Affiliation(s)
- Joseph A Duncan
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041, USA
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24
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Clément L, Kim-Sohn KA, Magnan C, Kassis N, Adnot P, Kergoat M, Assimacopoulos-Jeannet F, Pénicaud L, Hsu F, Turk J, Ktorza A. Pancreatic beta-cell alpha2A adrenoceptor and phospholipid changes in hyperlipidemic rats. Lipids 2002; 37:501-6. [PMID: 12056593 DOI: 10.1007/s11745-002-0924-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We previously showed that a 48-h intravenous lipid infusion in rats induces pancreatic beta-cell hypersensitivity to catecholamines. Our aim was to study the lipid-related changes that may account for such hypersensitivity in pancreatic islets. We show here that a 48-h increase in plasma FFA alters the binding characteristics of beta-cell alpha2 adrenoceptors in rats. Lipid infusion decreases pancreatic norepinephrine (NE) turnover rate by 28%, reflecting a reduction of pancreatic NE stores. Following lipid infusion, the density of alpha2 adrenoceptor binding sites is significantly lower and receptor affinity higher, both in islet homogenates (by three- and fivefold, respectively) and isolated whole beta-cells (by two- and sixfold, respectively). These changes correlate with the elevated insulin response to glucose found in lipid-infused rats. We also found a modification of islet phospholipid content, particularly in phosphoethanolamine species containing infused FA such as palmitate, oleate, stearate, and linoleate. This may account for the modifications in receptor affinity. These results suggest that hyperlipidemia-associated pathologies such as diabetes and obesity not only may result from alterations of metabolic pathways but also may be a consequence of early modifications in nervous firing rates and signal transduction pathways.
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MESH Headings
- Animals
- Catecholamines/blood
- Fatty Acids, Nonesterified/blood
- Glycerol/blood
- Hyperlipidemias/blood
- Hyperlipidemias/complications
- Hyperlipidemias/metabolism
- Insulin/blood
- Islets of Langerhans/metabolism
- Male
- Norepinephrine/metabolism
- Phospholipids/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Rats
- Rats, Wistar
- Receptors, Adrenergic, alpha-2/genetics
- Receptors, Adrenergic, alpha-2/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Spectrometry, Mass, Electrospray Ionization
- Triglycerides/blood
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Affiliation(s)
- L Clément
- Laboratoire de Physiopathologie de la Nutrition, CNRS UMR 7059, Université Paris 7, France.
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25
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Ponimaskin EG, Heine M, Joubert L, Sebben M, Bickmeyer U, Richter DW, Dumuis A. The 5-hydroxytryptamine(4a) receptor is palmitoylated at two different sites, and acylation is critically involved in regulation of receptor constitutive activity. J Biol Chem 2002; 277:2534-46. [PMID: 11706023 DOI: 10.1074/jbc.m106529200] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have reported recently that the mouse 5-hydroxytryptamine(4a) (5-HT(4(a))) receptor undergoes dynamic palmitoylation (Ponimaskin, E. G., Schmidt, M. F., Heine, M., Bickmeyer, U., and Richter, D. W. (2001) Biochem. J. 353, 627-663). In the present study, conserved cysteine residues 328/329 in the carboxyl terminus of the 5-HT(4(a)) receptor were identified as potential acylation sites. In contrast to other palmitoylated G-protein-coupled receptors, the additional cysteine residue 386 positioned close to the COOH-terminal end of the receptor was also found to be palmitoylated. Using pulse and pulse-chase labeling techniques, we demonstrated that palmitoylation of individual cysteines is a reversible process and that agonist stimulation of the 5-HT(4(a)) receptor independently increases the rate of palmitate turnover for both acylation sites. Analysis of acylation-deficient mutants revealed that non-palmitoylated 5-HT(4(a)) receptors were indistinguishable from the wild type in their ability to interact with G(s), to stimulate the adenylyl cyclase activity and to activate cyclic nucleotide-sensitive cation channels after agonist stimulation. The most distinctive finding of the present study was the ability of palmitoylation to modulate the agonist-independent constitutive 5-HT(4(a)) receptor activity. We demonstrated that mutation of the proximal palmitoylation site (Cys(328) --> Ser/Cys(329) --> Ser) significantly increases the capacity of receptors to convert from the inactive (R) to the active (R*) form in the absence of agonist. In contrast, the rate of isomerization from R to R* for the Cys(386) --> Ser as well as for the triple, non-palmitoylated mutant (Cys(328) --> Ser/Cys(329) --> Ser/Cys(386) -->Ser) was similar to that obtained for the wild type.
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Affiliation(s)
- Evgeni G Ponimaskin
- Abteilung Neuro- und Sinnesphysiologie, Physiologisches Institut, Universität Göttingen, Humboldtallee 23, D-37073 Göttingen, Germany
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26
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Lipidated peptides as tools for understanding the membrane interactions of lipid-modified proteins. PEPTIDE-LIPID INTERACTIONS 2002. [DOI: 10.1016/s1063-5823(02)52015-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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27
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Chaar ZY, Jackson A, Tiberi M. The cytoplasmic tail of the D1A receptor subtype: identification of specific domains controlling dopamine cellular responsiveness. J Neurochem 2001; 79:1047-58. [PMID: 11739618 DOI: 10.1046/j.1471-4159.2001.00648.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In this study the rat D1A receptor (wild-type, WT) and truncation mutants thereof, are utilized to delineate specific cytoplasmic tail (CT) domains responsible for regulating ligand binding and receptor-mediated adenylyl cyclase activation. In human embryonic kidney (HEK) cells, all truncation mutants of the D1A receptor (Delta425, Delta379, Delta351) display cell surface localization and express at high but different receptor numbers. Binding studies suggest that residues located between Cys(351) and Asp(425) may serve to restrain the agonist binding conformation of the D1A receptor. This contention is supported by the observation that the constitutive activation of Delta351 is significantly increased in comparison with WT, Delta425 and Delta379. Furthermore, we demonstrate that the extent of dopamine-mediated maximal activation of adenylyl cyclase is significantly augmented in cells expressing Delta351 when compared with WT or mutants harboring shorter truncations. These results suggest that in addition to restraining receptor conformation, determinants located downstream of Cys(351) may act as negative regulators of the G protein coupling efficiency and adenylyl cyclase activation. Interestingly, all truncated receptors used in the present study display a decrease in dopamine potency when compared with WT. We show that inhibition of protein kinase A (PKA) activity leads also to a reduction in dopamine potency in cells expressing WT but not Delta351 receptors. These results hint at a potential previously unanticipated role for PKA in facilitating D1A receptor coupling efficiency in HEK cells. Overall, the present study has uncovered specific CT domains involved in regulating discrete aspects of the D1A receptor signaling.
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Affiliation(s)
- Z Y Chaar
- Ottawa Health Research Institute, and Departments of Medicine/Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
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28
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Kozlova NO, Bruskovskaya IB, Okuneva IB, Melik-Nubarov NS, Yaroslavov AA, Kabanov VA, Menger FM. Interaction of a cationic polymer with negatively charged proteoliposomes. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1514:139-51. [PMID: 11513811 DOI: 10.1016/s0005-2736(01)00381-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Proteoliposomes were prepared by making bilayer vesicles from neutral egg yolk lecithin and negatively charged alpha-chymotrypsin that had been previously stearoylated. Interaction of these proteoliposomes with a cationic polymer, poly-(N-ethyl-4-vinylpryidinium bromide) (PEVP) was examined. For comparison purposes, interaction of PEVP with egg lecithin vesicles containing an anionic phospholipid, cardiolipin, was also examined. Binding of PEVP to both types of vesicles was electrostatic in nature with the polymer manifesting a higher affinity to the cardiolipin relative to the enzyme. PEVP had no effect on the permeability of the bilayer membranes to sodium chloride. On the other hand, PEVP increased the transmembrane permeability of the nonionic anti-tumor drug, doxorubicin. The greater the negatively charged component in the membrane, the greater the PEVP effect. Polycation binding to the vesicles was accompanied by clustering of the stearoylated chymotrypsin (sCT) molecules within the membrane. This protein clustering is most likely responsible for the increase in the doxorubicin permeation. Enzymatic activity of the membrane-associated sCT remained unchanged upon PEVP binding. These findings seem relevant to the effects of polyelectrolytes on cellular membranes.
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Affiliation(s)
- N O Kozlova
- Polymer Department, School of Chemistry, Lomonosov Moscow State University, Leninskie Gory, Russia
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29
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Percherancier Y, Planchenault T, Valenzuela-Fernandez A, Virelizier JL, Arenzana-Seisdedos F, Bachelerie F. Palmitoylation-dependent control of degradation, life span, and membrane expression of the CCR5 receptor. J Biol Chem 2001; 276:31936-44. [PMID: 11390405 DOI: 10.1074/jbc.m104013200] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have shown that the chemokine and HIV receptor CCR5 is palmitoylated on a cluster of cysteine residues located at the boundary between the seventh transmembrane region and the cytoplasmic tail. Single or combined substitutions of the three cysteines (Cys-321, Cys-323, and Cys-324) or incubation of wild-type CCR5-transfected cells with the palmitic acid analog 2-bromopalmitate prevented palmitoylation of the receptor. Moreover, failure of CCR5 to be palmitoylated resulted in both accumulation in intracellular stores and a profound decrease of membrane expression of the receptor. Upon metabolic labeling, kinetic experiments showed that the half-life of palmitoylation-deficient CCR5 is profoundly decreased. Bafilomycin A1, but not a specific proteasome inhibitor, prevented early degradation of palmitoylation-deficient CCR5 and promoted its accumulation in lysosomal compartments. Although membrane expression of the CCR5 mutant was diminished, the molecules reaching the membrane were still able to interact efficiently with the chemokine ligand MIP1 beta and remained able to function as HIV co-receptors. Thus we conclude that palmitoylation controls CCR5 expression through regulation of the life span of this receptor.
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Affiliation(s)
- Y Percherancier
- Institut Pasteur, Unité d'Immunologie Virale, 25-28 rue du Dr. Roux, 75724 Paris, cedex 15, France
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30
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Haagsman HP, Diemel RV. Surfactant-associated proteins: functions and structural variation. Comp Biochem Physiol A Mol Integr Physiol 2001; 129:91-108. [PMID: 11369536 DOI: 10.1016/s1095-6433(01)00308-7] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Pulmonary surfactant is a barrier material of the lungs and has a dual role: firstly, as a true surfactant, lowering the surface tension; and secondly, participating in innate immune defence of the lung and possibly other mucosal surfaces. Surfactant is composed of approximately 90% lipids and 10% proteins. There are four surfactant-specific proteins, designated surfactant protein A (SP-A), SP-B, SP-C and SP-D. Although the sequences and post-translational modifications of SP-B and SP-C are quite conserved between mammalian species, variations exist. The hydrophilic surfactant proteins SP-A and SP-D are members of a family of collagenous carbohydrate binding proteins, known as collectins, consisting of oligomers of trimeric subunits. In view of the different roles of surfactant proteins, studies determining the structure-function relationships of surfactant proteins across the animal kingdom will be very interesting. Such studies may reveal structural elements of the proteins required for surface film dynamics as well as those required for innate immune defence. Since SP-A and SP-D are also present in extrapulmonary tissues, the hydrophobic surfactant proteins SP-B and SP-C may be the most appropriate indicators for the evolutionary origin of surfactant. SP-B is essential for air-breathing in mammals and is therefore largely conserved. Yet, because of its unique structure and its localization in the lung but not in extrapulmonary tissues, SP-C may be the most important indicator for the evolutionary origin of surfactant.
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Affiliation(s)
- H P Haagsman
- Department of Biochemistry, Cell Biology and Histology and Graduate School of Animal Health, Utrecht University, P.O. Box 80175, 3508 TD, Utrecht, The Netherlands.
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31
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Blanpain C, Wittamer V, Vanderwinden JM, Boom A, Renneboog B, Lee B, Le Poul E, El Asmar L, Govaerts C, Vassart G, Doms RW, Parmentier M. Palmitoylation of CCR5 is critical for receptor trafficking and efficient activation of intracellular signaling pathways. J Biol Chem 2001; 276:23795-804. [PMID: 11323418 DOI: 10.1074/jbc.m100583200] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
CCR5 is a CC chemokine receptor expressed on memory lymphocytes, macrophages, and dendritic cells and also constitutes the main coreceptor for macrophage-tropic (or R5) strains of human immunodeficiency viruses. In the present study, we investigated whether CCR5 was palmitoylated in its carboxyl-terminal domain by generating alanine substitution mutants for the three cysteine residues present in this region, individually or in combination. We found that wild-type CCR5 was palmitoylated, but a mutant lacking all three Cys residues was not. Through the use of green fluorescent fusion proteins and immunofluorescence studies, we found that the absence of receptor palmitoylation resulted in sequestration of CCR5 in intracellular biosynthetic compartments. By using the fluorescence recovery after photobleaching technique, we showed that the non-palmitoylated mutant had impaired diffusion properties within the endoplasmic reticulum. We next studied the ability of the mutants to bind and signal in response to chemokines. Chemokines binding and activation of G(i)-mediated signaling pathways, such as calcium mobilization and inhibition of adenylate cyclase, were not affected. However, the duration of the functional response, as measured by a microphysiometer, and the ability to increase [(35)S]guanosine 5'-3-O-(thio)triphosphate binding to membranes were severely affected for the non-palmitoylated mutant. The ability of RANTES (regulated on activation normal T cell expressed and secreted) and aminooxypentane-RANTES to promote CCR5 endocytosis was not altered by cysteine replacements. Finally, we found that the absence of receptor palmitoylation reduced the human immunodeficiency viruses coreceptor function of CCR5, but this effect was secondary to the reduction in surface expression. In conclusion, we found that palmitoylated cysteines play an important role in the intracellular trafficking of CCR5 and are likely necessary for efficient coupling of the receptor to part of its repertoire of signaling cascades.
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Affiliation(s)
- C Blanpain
- Institute of Interdisciplinary Research, Laboratoire de Neurophysiologie, Laboratoire d'Histologie de Neuroanatomie et de Neuropathologie, and Service de Génétique Médicale, Université Libre de Bruxelles, Belgium
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32
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Bélanger C, Ansanay H, Qanbar R, Bouvier M. Primary sequence requirements for S-acylation of beta(2)-adrenergic receptor peptides. FEBS Lett 2001; 499:59-64. [PMID: 11418112 DOI: 10.1016/s0014-5793(01)02513-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Palmitoylation is a post-translational modification that occurs on selected cysteines of many proteins. Since a high proportion of basic and hydrophobic residues is often found near the palmitoylated cysteine, the role of these residues in the selection of specific palmitoylation sites was assessed. Short peptides derived from the beta(2)-adrenergic receptor sequence, modified to present different proportions of basic, acidic and hydrophobic residues, were tested in an in vitro S-acylation assay. Basic residues proved to be essential, whereas hydrophobic residues greatly enhanced S-acylation and acidic residues inhibited it. Taken together, these results show that short peptides contain the required molecular determinants leading to selective S-acylation. Whether or not these sequence characteristics also contribute to the selectivity of palmitoylation in vivo will need to be further investigated.
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Affiliation(s)
- C Bélanger
- Département de Biochimie and Groupe de Recherche sur le Système Nerveux Autonome, Université de Montréal, C.P. 6128, succursale Centre-Ville, H3C 3J7, Montréal, QC, Canada
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33
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Munshi UM, Peegel H, Menon KM. Palmitoylation of the luteinizing hormone/human chorionic gonadotropin receptor regulates receptor interaction with the arrestin-mediated internalization pathway. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:1631-9. [PMID: 11248681 DOI: 10.1046/j.1432-1327.2001.02032.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The luteinizing hormone/human chorionic gonadotropin receptor (LH/hCGR) undergoes palmitoylation at cysteine residues 621 and 622 located in the carboxyl terminal tail of the receptor. This study examined the biological function of palmitoylation with respect to its effect on receptor internalization. Coexpression of wild-type (WT) or C621/622G mutant receptors with arrestin-2 increased receptor internalization in 293T cells. Furthermore, measurements of rate enhancement upon overexpression of arrestin indicate that the palmitoylation deficient mutant receptor is more prone to utilizing the arrestin mediated internalization pathway than the WT receptor. Coexpression of G-protein-coupled receptor kinase 4 (GRK4) with wild type receptor resulted in an increase in internalization, while coexpression with the mutant receptor did not result in further enhancement of internalization. Additionally, 293T cells expressing mutant receptor were responsive to hCG with respect to production of inositol phosphates. Taken together, these results suggest that the palmitoylation state of the receptor governs internalization by regulating the accessibility of the receptor to the arrestin-mediated internalization pathway.
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Affiliation(s)
- U M Munshi
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA
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8 Reversible modification of proteins with thioester-linked fatty acids. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s1874-6047(01)80021-4] [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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35
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Devedjiev Y, Dauter Z, Kuznetsov SR, Jones TL, Derewenda ZS. Crystal structure of the human acyl protein thioesterase I from a single X-ray data set to 1.5 A. Structure 2000; 8:1137-46. [PMID: 11080636 DOI: 10.1016/s0969-2126(00)00529-3] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND Many proteins undergo posttranslational modifications involving covalent attachment of lipid groups. Among them is palmitoylation, a dynamic, reversible process that affects trimeric G proteins and Ras and constitutes a regulatory mechanism for signal transduction pathways. Recently, an acylhydrolase previously identified as lysophospholipase has been shown to function as an acyl protein thioesterase, which catalyzes depalmitoylation of Galpha proteins as well as Ras. Its amino acid sequence suggested that the protein is evolutionarily related to neutral lipases and other thioesterases, but direct structural information was not available. RESULTS We have solved the crystal structure of the human putative Galpha-regulatory protein acyl thioesterase (hAPT1) with a single data set collected from a crystal containing the wild-type protein. The phases were calculated to 1.8 A resolution based on anomalous scattering from Br(-) ions introduced in the cryoprotectant solution in which the crystal was soaked for 20 s. The model was refined against data extending to a resolution of 1.5 A to an R factor of 18.6%. The enzyme is a member of the ubiquitous alpha/beta hydrolase family, which includes other acylhydrolases such as the palmitoyl protein thioesterase (PPT1). CONCLUSIONS The human APT1 is closely related to a previously described carboxylesterase from Pseudomonas fluorescens. The active site contains a catalytic triad of Ser-114, His-203, and Asp-169. Like carboxylesterase, hAPT1 appears to be dimeric, although the mutual disposition of molecules in the two dimers differs. Unlike carboxylesterase, the substrate binding pocket and the active site of hAPT1 are occluded by the dimer interface, suggesting that the enzyme must dissociate upon interaction with substrate.
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Affiliation(s)
- Y Devedjiev
- Department of Molecular Physiology and Biological Physics, University of Virginia Health Sciences System Charlottesville, VA 22908, USA
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36
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Veldhuizen EJ, Haagsman HP. Role of pulmonary surfactant components in surface film formation and dynamics. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1467:255-70. [PMID: 11030586 DOI: 10.1016/s0005-2736(00)00256-x] [Citation(s) in RCA: 161] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Pulmonary surfactant is a mixture of lipids and proteins which is secreted by the epithelial type II cells into the alveolar space. Its main function is to reduce the surface tension at the air/liquid interface in the lung. This is achieved by forming a surface film that consists of a monolayer which is highly enriched in dipalmitoylphosphatidylcholine and bilayer lipid/protein structures closely attached to it. The molecular mechanisms of film formation and of film adaptation to surface changes during breathing in order to remain a low surface tension at the interface, are unknown. The results of several model systems give indications for the role of the surfactant proteins and lipids in these processes. In this review, we describe and compare the model systems that are used for this purpose and the progress that has been made. Despite some conflicting results using different techniques, we conclude that surfactant protein B (SP-B) plays the major role in adsorption of new material into the interface during inspiration. SP-C's main functions are to exclude non-DPPC lipids from the interface during expiration and to attach the bilayer structures to the lipid monolayer. Surfactant protein A (SP-A) appears to promote most of SP-B's functions. We describe a model proposing that SP-A and SP-B create DPPC enriched domains which can readily be adsorbed to create a DPPC-rich monolayer at the interface. Further enrichment in DPPC is achieved by selective desorption of non-DPPC lipids during repetitive breathing cycles.
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Affiliation(s)
- E J Veldhuizen
- Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, The Netherlands
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Paturiaux-Hanocq F, Hanocq-Quertier J, de Almeida ML, Nolan DP, Pays A, Vanhamme L, Van den Abbeele J, Wasunna CL, Carrington M, Pays E. A role for the dynamic acylation of a cluster of cysteine residues in regulating the activity of the glycosylphosphatidylinositol-specific phospholipase C of Trypanosoma brucei. J Biol Chem 2000; 275:12147-55. [PMID: 10766850 DOI: 10.1074/jbc.275.16.12147] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The glycosylphosphatidylinositol-specific phospholipase C or VSG lipase is the enzyme responsible for the cleavage of the glycosylphosphatidylinositol anchor of the variant surface glycoprotein (VSG) and concomitant release of the surface coat in Trypanosoma brucei during osmotic shock or extracellular acidic stress. In Xenopus laevis oocytes the VSG lipase was expressed as a nonacylated and a thioacylated form. This thioacylation occurred within a cluster of three cysteine residues but was not essential for catalytic activity per se. These two forms were also detected in trypanosomes and appeared to be present at roughly equivalent amounts. A reversible shift to the acylated form occurred when cells were triggered to release the VSG by either nonlytic acid stress or osmotic lysis. A wild type VSG lipase or a gene mutated in the three codons for the acylated cysteines were reinserted in the genome of a trypanosome null mutant for this gene. A comparative analysis of these revertant trypanosomes indicated that thioacylation might be involved in regulating enzyme access to the VSG substrate.
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Affiliation(s)
- F Paturiaux-Hanocq
- Department of Molecular Biology, Université Libre de Bruxelles, 12 rue des Profs Jeener et Brachet, B-6041, Gosselies, Belgium
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38
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Yu CR, Peden KW, Zaitseva MB, Golding H, Farber JM. CCR9A and CCR9B: two receptors for the chemokine CCL25/TECK/Ck beta-15 that differ in their sensitivities to ligand. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 164:1293-305. [PMID: 10640743 DOI: 10.4049/jimmunol.164.3.1293] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We isolated cDNAs for a chemokine receptor-related protein having the database designation GPR-9-6. Two classes of cDNAs were identified from mRNAs that arose by alternative splicing and that encode receptors that we refer to as CCR9A and CCR9B. CCR9A is predicted to contain 12 additional amino acids at its N terminus as compared with CCR9B. Cells transfected with cDNAs for CCR9A and CCR9B responded to the chemokine CC chemokine ligand 25 (CCL25)/thymus-expressed chemokine (TECK)/chemokine beta-15 (CK beta-15) in assays for both calcium flux and chemotaxis. No other chemokines tested produced responses specific for the cDNA-transfected cells. mRNA for CCR9A/B is expressed predominantly in the thymus, coincident with the expression of CCL25, and highest expression for CCR9A/B among thymocyte subsets was found in CD4+CD8+ cells. mRNAs encoding the A and B forms of the receptor were expressed at a ratio of approximately 10:1 in immortalized T cell lines, in PBMC, and in diverse populations of thymocytes. The EC50 of CCL25 for CCR9A was lower than that for CCR9B, and CCR9A was desensitized by doses of CCL25 that failed to silence CCR9B. CCR9 is the first example of a chemokine receptor in which alternative mRNA splicing leads to proteins of differing activities, providing a mechanism for extending the range of concentrations over which a cell can respond to increments in the concentration of ligand. The study of CCR9A and CCR9B should enhance our understanding of the role of the chemokine system in T cell biology, particularly during the stages of thymocyte development.
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Affiliation(s)
- C R Yu
- Laboratory of Clinical Investigation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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39
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Koziak K, Kaczmarek E, Kittel A, Sévigny J, Blusztajn JK, Schulte Am Esch J, Imai M, Guckelberger O, Goepfert C, Qawi I, Robson SC. Palmitoylation targets CD39/endothelial ATP diphosphohydrolase to caveolae. J Biol Chem 2000; 275:2057-62. [PMID: 10636909 DOI: 10.1074/jbc.275.3.2057] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ectonucleotidases influence purinergic receptor function by the hydrolysis of extracellular nucleotides. CD39 is an integral membrane protein that is a prototype member of the nucleoside 5'-triphosphate diphosphohydrolase family. The native CD39 protein has two intracytoplasmic and two transmembrane domains. There is a large extracellular domain that undergoes extensive glycosylation and can be post-translationally modified by limited proteolysis. We have identified a potential thioester linkage site for S-acylation within the N-terminal region of CD39 and demonstrate that this region undergoes palmitoylation in a constitutive manner. The covalent lipid modification of this region of the protein appears to be important both in plasma membrane association and in targeting CD39 to caveolae. These specialized plasmalemmal domains are enriched in G protein-coupled receptors and appear to integrate cellular activation events. We suggest that palmitoylation could modulate the function of CD39 in regulating cellular signal transduction pathways.
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Affiliation(s)
- K Koziak
- Department of Medicine, Center for Immunobiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
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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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41
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Energy, structure, conformation, and heart failure. Bull Exp Biol Med 1999. [DOI: 10.1007/bf02433812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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42
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Evans BA, Papaioannou M, Hamilton S, Summers RJ. Alternative splicing generates two isoforms of the beta3-adrenoceptor which are differentially expressed in mouse tissues. Br J Pharmacol 1999; 127:1525-31. [PMID: 10455305 PMCID: PMC1760668 DOI: 10.1038/sj.bjp.0702688] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The beta3-adrenoceptor (AR) differs from the beta1-AR and beta2-ARs in having introns within and downstream of the coding block. This study demonstrates two splice variants of the mouse beta3-AR which differ within the coding region. Reverse transcription/polymerase chain reaction with intron-spanning primers was used to demonstrate the splice variant of the mouse beta3-adrenoceptor. The novel beta3b-AR has 17 amino acids encoded by exon 2 (SSLLREPRHLYTCLGYP) which differ from the 13 in the known beta3a-AR (RFDGYEGARPFPT). Beta3b-AR mRNA is differentially expressed in mouse tissues, with levels relative to beta3a-AR mRNA highest in hypothalamus, cortex and white adipose tissue, and lower in ileum smooth muscle and brown adipose tissue.
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MESH Headings
- Adipose Tissue/metabolism
- Alternative Splicing
- Amino Acid Sequence
- Animals
- Base Sequence
- Cerebral Cortex/metabolism
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- Gene Expression Regulation
- Hypothalamus/metabolism
- Ileum/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Molecular Sequence Data
- Muscle, Smooth/metabolism
- Protein Isoforms/genetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Adrenergic, beta/genetics
- Receptors, Adrenergic, beta-3
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Analysis, DNA
- Tissue Distribution
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Affiliation(s)
- B A Evans
- Department of Pharmacology, Monash University, Clayton, Victoria 3168, Australia
| | - M Papaioannou
- Department of Pharmacology, Monash University, Clayton, Victoria 3168, Australia
| | - S Hamilton
- Department of Pharmacology, Monash University, Clayton, Victoria 3168, Australia
| | - R J Summers
- Department of Pharmacology, Monash University, Clayton, Victoria 3168, Australia
- Author for correspondence:
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43
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Zhang G, Contos JJ, Weiner JA, Fukushima N, Chun J. Comparative analysis of three murine G-protein coupled receptors activated by sphingosine-1-phosphate. Gene 1999; 227:89-99. [PMID: 9931453 DOI: 10.1016/s0378-1119(98)00589-7] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The cloning and analysis of the first identified lysophosphatidic acid (LPA) receptor gene, lpA1 (also referred to as vzg-1 or edg-2), led us to identify homologous murine genes that might also encode receptors for related lysophospholipid ligands. Three murine genomic clones (designated lpB1, lpB2, and lpB3) were isolated, corresponding to human/rat Edg-1, rat H218/AGR16, and human edg-3, respectively. Based on the amino acid similarities of their predicted proteins (44-52% identical), the three lpB genes could be grouped into a separate G-protein coupled receptor subfamily, distinct from that containing the LPA receptor genes lpA1 and lpA2. Unlike lpA1 and lpA2, which contain multiple coding exons, all lpB members contained a single coding exon. Heterologous expression of individual lpB members in a hepatoma cell line (RH7777), followed by 35S-GTPgammaS incorporation assays demonstrated that each of the three LPB receptors conferred sphingosine-1-phosphate-dependent, but not lysophosphatidic acid-dependent, G-protein activation. Northern blot and in situ hybridization analyses revealed overlapping as well as distinct expression patterns in both embryonic and adult tissues. This comparative characterization of multiple sphingosine-1-phosphate receptor genes and their spatiotemporal expression patterns will aid in understanding the biological roles of this enlarging lysophospholipid receptor family.
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Affiliation(s)
- G Zhang
- Department of Pharmacology, School of Medicine, University of California, San Diego, La Jolla, CA 92093-0636, USA
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44
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Veldhuizen EJ, Batenburg JJ, Vandenbussche G, Putz G, van Golde LM, Haagsman HP. Production of surfactant protein C in the baculovirus expression system: the information required for correct folding and palmitoylation of SP-C is contained within the mature sequence. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1416:295-308. [PMID: 9889385 DOI: 10.1016/s0005-2736(98)00230-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Surfactant protein C (SP-C) is synthesized in the alveolar type II cells of the lung as a 21 kDa propeptide which is proteolytically processed to a 4.2 kDa mature active form. The main function of this extremely hydrophobic protein is to enhance lipid insertion into the air/liquid interface in the lung upon inhalation. This is necessary to maintain a relatively low surface tension at this interface during breathing. In this report we describe the production of mature human SP-C in the baculovirus expression system. The recombinant protein contains a secondary structure with a high alpha-helical content (73%), comparable to native SP-C, as determined by circular dichroism and attenuated total reflection Fourier transform infrared analysis. The expressed protein is a mixture of dipalmitoylated (15%) and non-palmitoylated SP-C. This suggests that the information required for palmitoylation is contained within the sequence of the mature protein. The activity of the protein to insert phospholipids into a preformed monolayer of lipids at an air/liquid interface was determined with a captive bubble surfactometer. Recombinant SP-C significantly reduced the surface tension at the air/liquid interface during dynamic expansion and compression. We conclude that correctly folded, dipalmitoylated and active SP-C can be expressed in the baculovirus expression system. Our results may facilitate investigations into the relation between structure and function of SP-C and into protein palmitoylation in general.
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Affiliation(s)
- E J Veldhuizen
- Laboratory of Veterinary Biochemistry and Institute of Biomembranes, Utrecht University, 3508 TD, Utrecht, The Netherlands
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45
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DeMar JC, Rundle DR, Wensel TG, Anderson RE. Heterogeneous N-terminal acylation of retinal proteins. Prog Lipid Res 1999; 38:49-90. [PMID: 10396602 DOI: 10.1016/s0163-7827(98)00020-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- J C DeMar
- Department of Biochemistry, Baylor College of Medicine, Houston, Texas 77030, USA
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46
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Abstract
We examined whether the mu opioid receptor was palmitoylated and attempted to determine sites of palmitoylation. Following metabolic labeling with [3H]palmitic acid and immunoaffinity purification of the mu opioid receptor, SDS-PAGE and fluorography revealed a broad labeled band with Mr of approximately 80 kDa in CHO cells stably expressing the rat mu receptor, but not in CHO cells transfected with the vector alone, indicating that the mu receptor is palmitoylated. Activation of the receptor with morphine did not affect the extent of palmitoylation. Hydroxylamine or dithiothreitol treatment removed most of the radioactivity, demonstrating that [3H]palmitic acid is incorporated into Cys residue(s) via thioester bond(s). Surprisingly, mutations of the only two Cys residues in the C-terminal domain did not reduce [3H]palmitic acid incorporation significantly. Thus, unlike many G-protein coupled receptors, the palmitoylation site(s) of the rat mu opioid receptor do(es) not reside in the C-terminal domain.
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Affiliation(s)
- C Chen
- Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140, USA
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47
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Wouters S, Leruth M, Decroly E, Vandenbranden M, Creemers JW, van de Loo JW, Ruysschaert JM, Courtoy PJ. Furin and proprotein convertase 7 (PC7)/lymphoma PC endogenously expressed in rat liver can be resolved into distinct post-Golgi compartments. Biochem J 1998; 336 ( Pt 2):311-6. [PMID: 9820806 PMCID: PMC1219873 DOI: 10.1042/bj3360311] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The intracellular compartmentalization in rat liver of the membrane-associated convertases furin and proprotein convertase 7 (PC7)/lymphoma PC (LPC) was investigated by analytical subcellular fractionation. In control animals, both enzymes were found to localize in fractions depleted of endoplasmic reticulum, cis-Golgi and lysosomal markers, but to co-distribute with the Golgi marker galactosyltransferase and the trans-Golgi network (TGN) marker TGN38. After overloading Golgi-derived vesicles with very-low-density lipoproteins (VLDL) by feeding rats with ethanol, the distribution of PC7/LPC was shifted markedly towards lower densities, in contrast with those of furin and the TGN marker. This provides support for the TGN localization of endogenously expressed furin and indicates that, at steady state, a considerable proportion of PC7/LPC may be associated with vesicles derived from the TGN.
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Affiliation(s)
- S Wouters
- Laboratoire de Chimie Physique des Macromolécules aux Interfaces (LCPMI), CP206/2, Université Libre de Bruxelles, Boulevard du Triomphe, B-1050 Brussels, Belgium.
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48
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Abstract
Endothelin receptor type B (ETb) is one of the two ET receptor subtypes, both of which belong to the G protein-coupled receptor (GPCR) superfamily. The primary amino acid sequence of ETb, published in 1990, predicted potential posttranslational modifications of the receptor protein, and in the last couple of years, we and others presented direct experimental evidence for palmitoylation and phosphorylation of ETb. Functional evaluation of both substitution and deletion mutants indicated a negative role on the part of these modifications in the ligand binding capacities and cellular sequestrations of the receptors. At least one of them, palmitoylation, however, appears to be critically involved in the coupling with G proteins.
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Affiliation(s)
- Y Okamoto
- Department of Pharmacology, Faculty of Medicine, Kyoto University, Kyoto 606, Japan
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49
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Ono K, Sakamoto A, Masaki T, Satake M. Desensitization of ET(A) endothelin receptor-mediated negative chronotropic response in right atria--species difference and intracellular mechanisms. Br J Pharmacol 1998; 125:787-97. [PMID: 9831916 PMCID: PMC1571041 DOI: 10.1038/sj.bjp.0702125] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
1. Desensitization of ET(A) endothelin receptor (ET(A)R) was compared between the rat and guinea-pig with regard to negative chronotropic response (NC) in the right atria (RA). 2. ET-1 (100 nM) produced distinct NC in the presence of BQ788 (300 nM), and positive chronotropic response (PC) in the presence of BQ123 (1 microM) in both species, showing that ETAR and ET(B) endothelin receptor (ET(B)R) mediate NC and PC, respectively. 3. Repetitive applications of ET-1 (50 nM) desensitized PC, and the second application only induced a strong NC in both species. Later applications of ET-1 produced virtually no response in the rat RA, whereas they produced BQ123-sensitive NCs repetitively in guinea-pig RA, exhibiting marked species difference in desensitization of ETAR-mediated NC. 4. Pretreatment with staurosporine (100 nM) prevented desensitization of ET(A)R in the rat RA altogether. However, phorbol 12-myristate 13-acetate (PMA, 300 nM) failed to induce, but rather hampered, desensitization of ET(A)R. 5. Partial amino acid sequencing of ET(A)Rs, spanning from the 2nd through the 4th intracellular loops, revealed that all the potential Ser/Thr phosphorylation sites, including a protein kinase C (PKC) site, are conserved among guinea-pigs, rats, rabbits, bovines and humans. 6. In guinea pig RA, pretreatment with okadaic acid (1 microg ml(-1)) and PMA did not facilitate desensitization of ET(A)R whereas these agents successfully desensitized ETAR during combined stimulation of beta-adrenoceptor and ET(A)R by isoproterenol (300 nM) and ET-1 (100 nM). 7. These results suggest that species differences in desensitization of ET(A)R are not caused by differences in the site(s) of, but caused by differences in the environment for phosphorylation of the receptor. Desensitization of ET(A)R appears to require phosphorylation of the receptor by PKC as well as a kinase stimulated by beta-adrenoceptor activation.
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Affiliation(s)
- K Ono
- Division of Chemical Pharmacology and Phytochemistry, National Institute of Health Sciences, Tokyo, Japan
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50
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Okamoto Y, Ninomiya H, Tanioka M, Sakamoto A, Miwa S, Masaki T. Cysteine residues in the carboxyl terminal domain of the endothelin-B receptor are required for coupling with G-proteins. J Cardiovasc Pharmacol 1998; 31 Suppl 1:S230-2. [PMID: 9595445 DOI: 10.1097/00005344-199800001-00064] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We demonstrate that the human endothelin-B (ETB) receptor incorporates [3H]palmitic acid. Mutation of three putative palmitoylated cysteine residues (amino acids 402, 403 and 405) in the carboxyl terminus into serine residues (C2/3/5S) completely prevented palmitoylation of ETB. When expressed in CHO cells, C2/3/5S was localized on the cell surface, retained high affinity for ET-1 and ET-3, and was rapidly internalized when bound to the ligand. However, unlike the wild-type ETB, C2/3/5S transmitted neither an inhibitory effect on adenylate cyclase nor a stimulatory effect on phospholipase C, indicating a critical role of palmitoylation in the coupling with G-proteins, regardless of the G-protein subtype. Truncation of the carboxyl terminus, including all or a part of the three cysteine residues, gave palmitoylation-negative and -positive deletion mutants, delta 402 and delta 403. Despite the absence of the cytoplasmic tail, both delta 402 and delta 403 showed essentially the same features as C2/3/5S, except that delta 403 did transmit a stimulatory effect on phospholipase C via a pertussis toxin-insensitive G-protein, most likely a member(s) of the Gq family. These results indicated a differential requirement for the carboxyl terminus downstream from the palmitoylation site in the coupling with G-protein subtypes, i.e., it is required for the coupling with Gi but not for that with Gq.
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Affiliation(s)
- Y Okamoto
- Department of Pharmacology, Faculty of Medicine, Kyoto University, Japan
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