title: Evidence that interspecies polymorphism in the human and rat cholecystokinin receptor-2 affects structure of the binding site for the endogenous agonist cholecystokinin.
abstract: The cholecystokinin (CCK) receptor-2 exerts very important central and peripheral functions by binding the neuropeptides cholecystokinin or gastrin. Because this receptor is a potential therapeutic target, great interest has been devoted to the identification of efficient antagonists. However, interspecies genetic polymorphism that does not alter cholecystokinin-induced signaling was shown to markedly affect activity of synthetic ligands. In this context, precise structural study of the agonist binding site on the human cholecystokinin receptor-2 is a prerequisite to elucidating the molecular basis for its activation and to optimizing properties of synthetic ligands. In this study, using site-directed mutagenesis and molecular modeling, we delineated the binding site for CCK on the human cholecystokinin receptor-2 by mutating amino acids corresponding to that of the rat homolog. By doing so, we demonstrated that, although resembling that of rat homolog, the human cholecystokinin receptor-2 binding site also displays important distinct structural features that were demonstrated by susceptibility to several point mutations (F120A, Y189A, H207A). Furthermore, docking of CCK in the human and rat cholecystokinin receptor-2, followed by dynamic simulations, allowed us to propose a plausible structural explanation of the experimentally observed difference between rat and human cholecystokinin-2 receptors.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale (INSERM), Institut Louis Bugnard, CHU Rangueil, 31432 Toulouse Cedex 4, France.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Langer
authors.forename: Irina G
authors.initials: IG
authors.lastname: Tikhonova
authors.forename: Marie-Agnès
authors.initials: MA
authors.lastname: Travers
authors.forename: Elodie
authors.initials: E
authors.lastname: Archer-Lahlou
authors.forename: Chantal
authors.initials: C
authors.lastname: Escrieut
authors.forename: Bernard
authors.initials: B
authors.lastname: Maigret
authors.forename: Daniel
authors.initials: D
authors.lastname: Fourmy
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007295:Inositol Phosphates / Q000737:chemistry; D007700:Kinetics; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009474:Neurons / Q000737:chemistry; D010455:Peptides / Q000737:chemistry; D011110:Polymorphism, Genetic; D011485:Protein Binding; D011487:Protein Conformation; D051381:Rats; D043887:Receptor, Cholecystokinin B / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D013045:Species Specificity; D014162:Transfection
chemical_list: D018076:DNA, Complementary; D007295:Inositol Phosphates; D008024:Ligands; D010455:Peptides; D043887:Receptor, Cholecystokinin B