title: Activation of G-protein Galpha subunits by receptors through Galpha-Gbeta and Galpha-Ggamma interactions.
abstract: Activation of the Galpha subunit of heterotrimeric GTP-binding proteins by transmembrane receptors requires the propagation of structural signals from the receptor-binding site to the nucleotide-binding site at the opposite side of the protein. In a previous model, it was suggested that the Gbeta-Ggamma dimer is tilted away from Galpha by a lever-arm motion of the Galpha N-terminal helix. Here, we propose that the motion occurs in the opposite direction, close-packing the Galpha-Gbeta interface and creating a novel interface between the helical domain of Galpha and the N terminus of Ggamma, which determines the specificity of activation.
authors.affiliation: Laboratoire d'Enzymologie et Biochimie Structurales, UPR 9063 CNRS, 1, avenue de la Terrasse, 91198 cedex, Gif sur Yvette, France. cherfils@lebs.cnrs-gif.fr
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Cherfils
authors.forename: Marc
authors.initials: M
authors.lastname: Chabre
mesh_terms: D019281:Dimerization; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D008958:Models, Molecular; D011485:Protein Binding; D011956:Receptors, Cell Surface / Q000378:metabolism*
chemical_list: D020662:Guanine Nucleotide Exchange Factors; D011956:Receptors, Cell Surface; D019204:GTP-Binding Proteins