title: Interaction of Gbeta3s, a splice variant of the G-protein Gbeta3, with Ggamma- and Galpha-proteins.
abstract: The T-allele of a polymorphism (C825T) in the gene of the G-protein beta3-subunit is associated with a complex phenotype (hypertension, obesity, altered drug responses) and the occurrence of a splice variant termed Gbeta3s which lacks one of the seven WD-domains that compose Gbeta-proteins. Here, we analysed Gbetagamma dimer formation and Galpha activation by Gbeta3s, key functional characteristics of Gbeta-proteins. Cleavage protection assays frequently used to analyse Gbeta1gamma and Gbeta2gamma dimer formation failed for Gbeta3 and Gbeta3s, while in coprecipitation assays, dimerization of Gbeta3 and Gbeta3s with Ggamma5, Ggamma8(c) and Ggamma12 could be demonstrated. Upon expression of Gbeta3s in COS-7 and Sf9 insect cells, binding of GTPgammaS to Galpha-proteins induced by mastoparan-7 and the M(2) muscarinic acetylcholine receptor was facilitated in comparison with cells overexpressing wildtype Gbeta3, as indicated by twofold reduced agonist EC(50) values. Together, these results indicate that Gbeta3s is a biologically active Gbeta-protein that may mediate the enhanced signal transduction observed in cells with the 825T-allele.
authors.affiliation: Institut für Pharmakologie, Universitätsklinikum Essen, Hufelandstrasse 55, D-45122 Essen, Germany. dieter.rosskopf@uni-essen.de
authors.forename: Dieter
authors.initials: D
authors.lastname: Rosskopf
authors.forename: Karin
authors.initials: K
authors.lastname: Koch
authors.forename: Christiane
authors.initials: C
authors.lastname: Habich
authors.forename: Jörg
authors.initials: J
authors.lastname: Geerdes
authors.forename: Axel
authors.initials: A
authors.lastname: Ludwig
authors.forename: Sabine
authors.initials: S
authors.lastname: Wilhelms
authors.forename: Karl H
authors.initials: KH
authors.lastname: Jakobs
authors.forename: Winfried
authors.initials: W
authors.lastname: Siffert
mesh_terms: D000818:Animals; D019556:COS Cells; D002460:Cell Line; D019281:Dimerization; D020962:Heterotrimeric GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D011233:Precipitin Tests; D021122:Protein Subunits; D012326:RNA Splicing
chemical_list: C454420:G-protein beta3 subunit; D021122:Protein Subunits; D020962:Heterotrimeric GTP-Binding Proteins