Mechanism of activation of a G protein-coupled receptor, the human cholecystokinin-2 receptor.

Abstract : G protein-coupled receptors (GPCRs) represent a major focus in functional genomics programs and drug development research, but their important potential as drug targets contrasts with the still limited data available concerning their activation mechanism. Here, we investigated the activation mechanism of the cholecystokinin-2 receptor (CCK2R). The three-dimensional structure of inactive CCK2R was homology-modeled on the basis of crystal coordinates of inactive rhodopsin. Starting from the inactive CCK2R modeled structure, active CCK2R (namely cholecystokinin-occupied CCK2R) was modeled by means of steered molecular dynamics in a lipid bilayer and by using available data from other GPCRs, including rhodopsin. By comparing the modeled structures of the inactive and active CCK2R, we identified changes in the relative position of helices and networks of interacting residues, which were expected to stabilize either the active or inactive states of CCK2R. Using targeted molecular dynamics simulations capable of converting CCK2R from the inactive to the active state, we delineated structural changes at the atomic level. The activation mechanism involved significant movements of helices VI and V, a slight movement of helices IV and VII, and changes in the position of critical residues within or near the binding site. The mutation of key amino acids yielded inactive or constitutively active CCK2R mutants, supporting this proposed mechanism. Such progress in the refinement of the CCK2R binding site structure and in knowledge of CCK2R activation mechanisms will enable target-based optimization of nonpeptide ligands.
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Journal of Biological Chemistry, American Society for Biochemistry and Molecular Biology, 2007, 282 (39), pp.28779-90. 〈10.1074/jbc.M700349200〉
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Soumis le : mardi 11 août 2009 - 15:56:02
Dernière modification le : mardi 25 août 2009 - 15:16:09

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Esther Marco, Magali Foucaud, Ingrid Langer, Chantal Escrieut, Irina Tikhonova, et al.. Mechanism of activation of a G protein-coupled receptor, the human cholecystokinin-2 receptor.. Journal of Biological Chemistry, American Society for Biochemistry and Molecular Biology, 2007, 282 (39), pp.28779-90. 〈10.1074/jbc.M700349200〉. 〈inserm-00409663〉

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