Key amino acids located within the transmembrane domains 5 and 7 account for the pharmacological specificity of the human V1b vasopressin receptor.
In mammals, the vasopressin V(1b) receptor (V(1b)-R) is known to regulate ACTH secretion and, more recently, stress and anxiety. The characterization of the molecular determinant responsible for its pharmacological selectivity was made possible by the recent discovery of the first V(1b) antagonist, SSR149415. Based upon the structure of the crystallized bovine rhodopsin, we established a three-dimensional molecular model of interaction between the human V(1b)-R (hV(1b)-R) and SSR149415. Four amino acids located in distinct transmembrane helices (fourth, fifth, and seventh) were found potentially responsible for the hV(1b)-R selectivity. To validate these assumptions, we selectively replaced the leucine 181, methionine 220, alanine 334, and serine 338 residues of hV(1a)-R by their corresponding amino acids present in the hV(1b)-R (phenylalanine 164, threonine 203, methionine 324, and asparagine 328, respectively). Four mutants, which all exhibited nanomolar affinities for vasopressin and good coupling to phospholipase C pathway, were generated. hV(1a) receptors mutated at position 220 and 334 exhibited striking increase in affinity for SSR149415 both in binding and phospholipase C assays at variance with the hV(1a)-R modified at position 181 or 338. In conclusion, this study provides the first structural features concerning the hV(1b)-R and highlights the role of few specific residues in its pharmacological selectivity.
Institut National de la Santé et de la Recherche Médicale, Unité 469, 141 rue de la Cardonille, 34094 Montpellier, Cedex 05, France.
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Derick
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Pena
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Durroux
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Wagnon
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Serradeil-Le Gal
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Hibert
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Rognan
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Guillon
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D000596:Amino Acids / Q000737:chemistry*; D000818:Animals; D065092:Antidiuretic Hormone Receptor Antagonists; D016466:CHO Cells; D002417:Cattle; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D007211:Indoles / Q000737:chemistry / Q000494:pharmacology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed / Q000235:genetics; D009154:Mutation / Q000235:genetics; D017434:Protein Structure, Tertiary; D011759:Pyrrolidines / Q000737:chemistry / Q000494:pharmacology*; D017483:Receptors, Vasopressin / Q000737:chemistry* / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry; D012243:Rhodopsin / Q000737:chemistry / Q000235:genetics; D016415:Sequence Alignment
C456029:1-(5-chloro-1-((2,4-dimethoxyphenyl)sulfonyl)-3-(2-methoxyphenyl)-2-oxo-2,3-dihydro-1H-indol-3-yl)-4-hydroxy-N,N-dimethyl-2-pyrrolidinecarboxamide; D000596:Amino Acids; D065092:Antidiuretic Hormone Receptor Antagonists; D007211:Indoles; D011759:Pyrrolidines; D017483:Receptors, Vasopressin; D011993:Recombinant Fusion Proteins; D012243:Rhodopsin