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Conserved aromatic residues in the transmembrane region VI of the V1a vasopressin receptor differentiate agonist vs. antagonist ligand binding
被引:35
作者:
Cotte, N
Balestre, MN
Aumelas, A
Mahé, E
Phalipou, S
Morin, D
Hibert, M
Manning, M
Durroux, T
Barberis, C
Mouillac, B
[1
]
机构:
[1] INSERM, U469, 141 Rue Cardonille, F-34094 Montpellier 05, France
[2] Fac Pharm Montpellier, CNRS, INSERM, UMR 5048,U414, Montpellier, France
[3] Fac Pharm Strasbourg, Lab Pharmacochim Commun Cellulaire, Illkirch Graffenstaden, France
[4] Med Coll Ohio, Dept Biochem & Mol Biol, Toledo, OH 43699 USA
来源:
EUROPEAN JOURNAL OF BIOCHEMISTRY
|
2000年
/
267卷
/
13期
关键词:
vasopressin receptors;
antagonist-binding sites;
signal transduction;
site-directed mutagenesis;
three-dimensional model;
D O I:
10.1046/j.1432-1033.2000.01472.x
中图分类号:
Q5 [生物化学];
Q7 [分子生物学];
学科分类号:
071010 ;
081704 ;
摘要:
Despite their opposite effects on signal transduction, the nonapeptide hormone arginine-vasopressin (AVP) and its V-1a receptor-selective cyclic peptide antagonist d(CH2)(5)[Tyr(Me)2]AVP display homologous primary structures, differing only at residues 1 and 2. These structural similarities led us to hypothesize that both ligands could interact with the same binding pocket in the V-1a receptor. To determine receptor residues responsible for discriminating binding of agonist and antagonist ligands, we performed site-directed mutagenesis of conserved aromatic and hydrophilic residues as well as nonconserved residues, all located in the transmembrane binding pocket of the V-1a receptor. Mutation of aromatic residues of transmembrane region VI (W304, F307, F308) reduced affinity for the d(CH2)(5)[Tyr(Me)2]AVP and markedly decreased affinity for the unrelated strongly hydrophobic V-1a-selective nonpeptide antagonist SR 49059. Replacement of these aromatic residues had no effect on AVP binding, but increased AVP-induced coupling efficacy of the receptor for its G protein. Mutating hydrophilic residues Q108, K128 and Q185 in transmembrane regions II, III and IV, respectively, led to a decrease in affinity for both agonists and antagonists. Finally, the nonconserved residues T333 and A334 in transmembrane region VII, controlled the V-1a/V-2 binding selectivity for both nonpeptide and cyclic peptide antagonists. Thus, because conserved aromatic residues of the V-1a receptor binding pocket seem essential for antagonists and do not contribute at all to the binding of agonists, we propose that these residues differentiate agonist vs. antagonist ligand binding.
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页码:4253 / 4263
页数:11
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