PT  - JOURNAL ARTICLE
AU  - Céline Galés
AU  - Marc Poirot
AU  - Julien Taillefer
AU  - Bernard Maigret
AU  - Jean Martinez
AU  - Luis Moroder
AU  - Chantal Escrieut
AU  - Lucien Pradayrol
AU  - Daniel Fourmy
AU  - Sandrine Silvente-Poirot
TI  - Identification of Tyrosine 189 and Asparagine 358 of the Cholecystokinin 2 Receptor in Direct Interaction with the Crucial C-Terminal Amide of Cholecystokinin by Molecular Modeling, Site-Directed Mutagenesis, and Structure/Affinity Studies
AID  - 10.1124/mol.63.5.973
DP  - 2003 May 01
TA  - Molecular Pharmacology
PG  - 973--982
VI  - 63
IP  - 5
4099  - http://molpharm.aspetjournals.org/content/63/5/973.short
4100  - http://molpharm.aspetjournals.org/content/63/5/973.full
SO  - Mol Pharmacol2003 May 01; 63
AB  - The cholecystokinin (CCK) receptors CCK1R and CCK2R exert important central and peripheral functions by binding the neuropeptide cholecystokinin. Because these receptors are potential therapeutic targets, great interest has been devoted to the identification of efficient ligands that selectively activate or inhibit these receptors. A complete mapping of the CCK binding site in these receptors would help to design new CCK ligands and to optimize their properties. In this view, a molecular model of the CCK2R occupied by CCK was built to identify CCK2R residues that interact with CCK functional groups. No such study has yet been reported for the CCK2R. Docking of CCK in the receptor was performed by taking into account our previous mutagenesis data and by using, as constraint, the direct interaction that we demonstrated between His207 in the CCK2R and Asp8 of CCK (Mol Pharmacol54:364–371, 1998; J Biol Chem274:23191–23197, 1999). Two residues that had not been revealed in our previous mutagenesis studies, Tyr189 (Y4.60) and Asn358 (N6.55), were identified in interaction via hydrogen bonds with the C-terminal amide of CCK, a crucial functional group of the peptide. Mutagenesis of Tyr189 (Y4.60) and Asn358 (N6.55) as well as structure-affinity studies with modified CCK analogs validated these interactions and the involvement of both residues in the CCK binding site. These results indicate that the present molecular model is an important tool to identify direct contact points between CCK and the CCK2R and to rapidly progress in mapping of the CCK2R binding site. Moreover, comparison of the present CCK2R.CCK molecular model with that of CCK1R.CCK, which we have previously published and validated, clearly argues that the positioning of CCK in these receptors is different. The American Society for Pharmacology and Experimental Therapeutics