Specificity of receptor-G protein interactions: Searching for the structure behind the signal

Hedin, Karen E.; Duerson, Kevin; Clapham, David E.

doi:10.1016/0898-6568(93)90046-o

Cited by 104 publications

(72 citation statements)

References 77 publications

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“…The movement of the transmembrane domains is transferred into the intracellular loop domains, thus altering the receptors intracellular surface and presenting previously hidden amino acid residues important for G coupling (Farahbakhsh et al, 1993;Farahbakhsh et al, 1995). The GPCRs are thought to trigger GDP release on the Ga subunit of the hetemtrimeric G protein by an allosteric mechanisrn, since the nucleotide is buried deep inside the Ga subunit and is unlikely to be in direct contact with the receptor (Bourne, 1997;Lambright et al, 1996;Wall et al, 1995;Wess, 1998) The identification of the receptor domains involved in G protein-coupling has been derived h m earl y studies with hybnd muscarinic and adrenergic subtypes and more recently with many other GPCRs ( D o b a n et al, 199 1 ; Hedin et al, 1993;Wess, 1998 and Fraser, 1992;Wess, 1997;Wess, 1998 Okamoto and Nishimoto, 1992) which çonfirm mutagenesis studies which indicate that these regions are important for coupling (Blin et al, 1995;Wong et al, 1990;Wong and Ross, 1994). Al1 these sites act in a cooperative fashion to determine both G protein selectivity and affinity of the GPCR (Blin et al, 1995;Wong et al, 1990; Ross, 1 994).…”

Section: G Protein-coupiing Of the Gpcrs And The Dopamine D4 Receptormentioning

confidence: 99%

SH3 Binding Domains in the Dopamine D4 Receptor

Oldenhof

Vickery²,

Anafi³

et al. 1998

Biochemistry

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The dopamine D4 receptor is a G protein-coupled receptor (GPCR) that belongs to the dopamine D2-like receptor family. Functionally, the D2-like receptors are characterized by their ability to inhibit adenylyl cyclase. The dopamine D4 receptor as well as many other catecholaminergic receptors contain several putative SH3 binding domains. Most of these sites in the D4 receptor are located in a polymorphic repeat sequence and flanking sequences in the third intracellular loop. Here we demonstrate that this region of the D4 receptor can interact with a large variety of SH3 domains of different origin. The strongest interactions were seen with the SH2−SH3 adapter proteins Grb2 and Nck. The repeat sequence itself is not essential in this interaction. The data presented indicate that the different SH3 domains in the adapter proteins interact in a cooperative fashion with two distinct sites immediately upstream and downstream from the repeat sequence. Removal of all the putative SH3 binding domains in the third intracellular loop of the dopamine D4 receptor resulted in a receptor that could still bind spiperone and dopamine. Dopamine could not modulate the coupling of these mutant receptors to adenylyl cyclase and MAPK, although dopamine modulated receptor−G protein interaction appeared normal. The receptor deletion mutants show strong constitutive internalization that may account for the deficiency in functional activation of second messengers. The data indicates that the D4 receptor contains SH3 binding sites and that these sites fall within a region involved in the control of receptor internalization.

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Section: G Protein-coupiing Of the Gpcrs And The Dopamine D4 Receptormentioning

confidence: 99%

SH3 Binding Domains in the Dopamine D4 Receptor

Oldenhof

Vickery²,

Anafi³

et al. 1998

Biochemistry

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“…Characteristically, a specific GPCR can interact with only a limited subset of the many structurally similar G proteins that are expressed within a cell. Molecular genetic and biochemical studies have identified distinct intracellular regions (as well as single amino acids contained within these domains) on the GPCR proteins that play key roles in determining the fidelity of receptor-G protein coupling (1)(2)(3)(4)(5)(6)(7). In addition, recent studies have shown that residues at the extreme C terminus of the G protein ␣ subunits are also of fundamental importance for the selectivity of receptor-G protein interactions (8 -10).…”

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confidence: 99%

The N-terminal Extension of Gαq Is Critical for Constraining the Selectivity of Receptor Coupling

Kostenis

Degtyarev²,

Conklin³

et al. 1997

Journal of Biological Chemistry

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Characteristically, an individual member of the superfamily of G protein-coupled receptors can interact only with a limited number of the many structurally closely related G protein heterotrimers that are expressed within a cell. Interestingly, the N termini of two G protein ␣ subunits, G␣ q and G␣ 11 , differ from those of other ␣ subunits in that they display a unique, highly conserved six-amino acid extension. To test the hypothesis that this sequence element is critical for proper receptor recognition, we prepared a G␣ q deletion mutant (؊6q) lacking these first six amino acids. The ؊6q construct (or wild type G␣ q as a control) was coexpressed (in COS-7 cells) with several different G i/o -or G s -coupled receptors, and ligand-induced increases in inositol phosphate production were determined as a measure of G protein activation. Whereas these receptors did not efficiently interact with wild type G␣ q , most of them gained the ability to productively couple to ؊6q. Additional experiments indicated that the observed functional promiscuity of ؊6q is not due to overexpression (as compared with wild type G␣ q ) or to a lack of palmitoylation. We conclude that the N-terminal extension characteristic for G␣ q/11 proteins is critical for constraining the receptor coupling selectivity of these subunits, indicative of a novel mechanism by which the fidelity of receptor-G protein interactions can be regulated.G protein-coupled receptors (GPCRs), 1 when activated by extracellular ligands, interact with specific classes of heterotrimeric G proteins (consisting of ␣, ␤, and ␥ subunits) which can then, in their activated forms, inhibit or activate various effector enzymes and/or ion channels (1-5). Characteristically, a specific GPCR can interact with only a limited subset of the many structurally similar G proteins that are expressed within a cell. Molecular genetic and biochemical studies have identified distinct intracellular regions (as well as single amino acids contained within these domains) on the GPCR proteins that play key roles in determining the fidelity of receptor-G protein coupling (1-7). In addition, recent studies have shown that residues at the extreme C terminus of the G protein ␣ subunits are also of fundamental importance for the selectivity of receptor-G protein interactions (8 -10). However, several lines of evidence suggest that the C terminus of the G␣ subunits is clearly not the only structural determinant on the G proteins that is critical for dictating receptor-G protein coupling selectivity (2, 5).Interestingly, two G protein ␣ subunits, G␣ q and G␣ 11 , contain a unique six-amino acid extension that is not found in other G␣ subunits (Fig. 1). This short sequence is highly conserved among all vertebrate species from which these subunits have been cloned so far (11)(12)(13)(14)(15), suggesting that it may be relevant for some aspect of G␣ q /G␣ 11 function.Previous studies (16,17) analyzing the biochemical properties of a mutant G␣ q subunit lacking the N-terminal extension (hereafter referred...

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“…The GIP receptor has been shown to stimulate adenylyl cyclase in pancreatic islet ␣-and ␤-cells (13), islet tumor cells (14 -16), and cell lines transfected with pancreatic GIP receptor cDNAs (4 -6). However little is known regarding the specific components of the GIP receptor, which are important for G-protein coupling or regulation of desensitization and internalization.Extensive mutagenesis and chimeric receptor studies on the ␤-adrenergic and cholinergic receptors have indicated that all of the intracellular loops of the seven transmembrane class of receptors can play a role in G-protein binding, although the NH 2 and COOH termini of the third intracellular loop are considered to be of primary importance for both G-protein binding and conferring specificity of action (17)(18)(19)(20). In recent studies on the GLP-1 receptor, which is very closely related to that for GIP, sequences in the proximal and distal portions of third intracellular loop were shown to be required for coupling to G s and adenylyl cyclase (21,22).…”

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confidence: 99%

Characterization of the Carboxyl-terminal Domain of the Rat Glucose-dependent Insulinotropic Polypeptide (GIP) Receptor

Wheeler¹,

Gelling²,

Hinke³

et al. 1999

Journal of Biological Chemistry

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Glucose-dependent insulinotropic polypeptide (GIP)is a gastrointestinal hormone involved in the regulation of insulin secretion. In non-insulin-dependent diabetes mellitus insulin responses to GIP are blunted, possibly due to altered signal transduction or reduced receptor number. Site-directed mutagenesis was used to construct truncated GIP receptors to study the importance of the carboxyl-terminal tail (CT) in binding, signaling, and receptor internalization. Receptors truncated at amino acids 425, 418, and 405, expressed in COS-7 or CHO-K1 cells, exhibited similar binding to wild type receptors. GIP-dependent cAMP production with the 405 mutant was decreased in COS-7 cells. Maximal cAMP production in CHO-K1 cells was reduced with all truncated forms. Binding was undetectable with a receptor truncated at amino acid 400; increasing tail length by adding 5 alanines restored binding and signaling. Mutants produced by alanine scanning of residues 394 -401, adjacent to transmembrane domain 7, were all functional. CT truncation by 30 or more amino acids, mutation of serines 426/427, singly or combined, or complete CT serine knockout all reduced receptor internalization rate. The majority of the GIP receptor CT is therefore not required for signaling, a minimum chain length of ϳ405 amino acids is needed for receptor expression, and serines 426 and 427 are important for regulating rate of receptor internalization.Incretins are peptide hormones released from the gastrointestinal tract into the circulation in response to a meal that potentiate glucose-stimulated insulin secretion. There are two established incretins: gastric inhibitory polypeptide/glucosedependent insulinotropic polypeptide (GIP) 1 and the truncated forms of glucagon-like peptide-1 (GLP-1). In non-insulin-dependent diabetes mellitus (NIDDM), the incretin effect following oral glucose is reduced or absent (1, 2), and the insulin response to intravenously administered GIP, but not GLP-1, has been reported to be severely blunted (2, 3). Possible explanations for a decreased responsiveness to GIP include a defective signal-transduction system and a reduction in the number of functional pancreatic islet receptors due to altered expression, mutation, or degree of desensitization and/or internalization. To elucidate which of these could be involved in reduced responsiveness, it is necessary to develop a greater understanding of the functional roles played by the different structural components of the GIP receptor. The receptor for GIP (4 -6) is a member of the seven transmembrane G-protein-coupled secretin-vasoactive intestinal peptide (VIP) family, which includes the receptors for glucagon (7), glucagon-like peptide-1 (8), secretin (9), VIP (10), parathyroid hormone/parathyroid hormone-related peptide (PTH/PTH-RP) (11), and calcitonin (12). The GIP receptor has been shown to stimulate adenylyl cyclase in pancreatic islet ␣-and ␤-cells (13), islet tumor cells (14 -16), and cell lines transfected with pancreatic GIP receptor cDNAs (4 -6). However little is kn...

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Specificity of receptor-G protein interactions: Searching for the structure behind the signal

Cited by 104 publications

References 77 publications

SH3 Binding Domains in the Dopamine D4 Receptor

SH3 Binding Domains in the Dopamine D4 Receptor

The N-terminal Extension of Gαq Is Critical for Constraining the Selectivity of Receptor Coupling

Characterization of the Carboxyl-terminal Domain of the Rat Glucose-dependent Insulinotropic Polypeptide (GIP) Receptor

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