title: G-protein betagamma-subunits contribute to the coupling specificity of the beta2-adrenergic receptor to G(s).
abstract: Receptors and heterotrimeric G-proteins interact with a high degree of specificity, the molecular basis of which is only partially understood. In the present study, we analyzed the influence of different G-protein betagamma-subunits on the coupling of the beta2-adrenergic receptor to G(s). Sf9-cells were infected with baculoviruses coding for the beta2-adrenergic receptor, alpha(s,Short) or alpha(s,Long), and various beta- and gamma-subunits. The ability of different beta- and gamma-subunits to correctly dimerize was assessed by limited proteolysis of proteins expressed in Sf9-cells and additionally by analysis of beta/gamma-interaction in the yeast two-hybrid system. Agonist-induced GTPgammaS-binding to alpha(s,Short)beta(1)gamma-trimers was significantly higher than to alpha(s,Short)beta2gamma-combinations, when gamma4, gamma5, or gamma7 were co-expressed. Because beta(5) did not support coupling of the beta(2)-adrenergic receptor to G(s), the 87 C-terminal amino acids of Gbeta(5) assumed to encompass the beta-subunit interface with the receptor were substituted by the corresponding sequence of beta(1). Whereas this beta(5)/beta(1)-chimera did not promote GTPgammaS-binding to alpha(s), histamine H(1)-receptor-dependent GTPgammaS-binding to alpha(q) was supported by this chimeric beta-subunit and by wild-type beta(5). Our findings argue that the betagamma-subunit composition contributes directly to the specificity of beta(2)-adrenergic receptor-mediated G(s)-activation.
authors.affiliation: Institut für Pharmakologie, Universitätsklinikum Benjamin Franklin, Freie Universität Berlin, Berlin, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Kühn
authors.forename: Constantin
authors.initials: C
authors.lastname: Christel
authors.forename: Thomas
authors.initials: T
authors.lastname: Wieland
authors.forename: Günter
authors.initials: G
authors.lastname: Schultz
authors.forename: Thomas
authors.initials: T
authors.lastname: Gudermann
mesh_terms: D000818:Animals; D016367:Baculoviridae / Q000235:genetics; D002460:Cell Line; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000378:metabolism*; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D005822:Genetic Vectors; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D007313:Insecta; D018343:Receptors, Adrenergic, beta-2 / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D015398:Signal Transduction; D014162:Transfection; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: C118981:G-protein Beta gamma; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D018343:Receptors, Adrenergic, beta-2; D011994:Recombinant Proteins; D001616:beta-Galactosidase; D019205:GTP-Binding Protein alpha Subunits, Gs; D020962:Heterotrimeric GTP-Binding Proteins