title: Binding of G protein beta gamma-subunits to pleckstrin homology domains.
abstract: Ligand-induced activation of many receptors leads to dissociation of the alpha- and beta gamma-subunit complexes of heterotrimeric G proteins, both of which regulate a variety of effector molecules involved in cellular signaling processes. In one case, a cytosolic enzyme, the beta-adrenergic receptor kinase (beta ARK) binds to the dissociated, prenylated, membrane-anchored beta gamma-subunits of heterotrimeric G proteins (G beta gamma) and is thereby targeted to its membrane-bound receptor substrate. Quite recently, numerous proteins involved in cellular signal transduction have been shown to contain sequences homologous with a "domain" originally identified in the protein "pleckstrin" (pleckstrin homology domain; PH domain) and subsequently found in the G beta gamma interaction region of the beta ARK sequence. Here we demonstrate that glutathione S-transferase-fusion proteins, containing sequences encompassing the PH domain of nine proteins from this group, bind G beta gamma to varying extents. Binding of G beta gamma to these fusion proteins was documented either by a direct binding assay or by ability to block G beta gamma-mediated membrane translocation of beta ARK1. G beta gamma binding to these fusion proteins was inhibited by the alpha subunit of Go (Go alpha), indicating that the binding of G beta gamma to G alpha and the PH domain-containing fusion proteins is mutually exclusive. Studies with a series of truncated PH domains derived from the Ras-guanine-nucleotide-releasing factor indicate that the G beta gamma binding domain includes only the C-terminal portion of the PH domain and sequences just distal to this. Protein-protein interactions between G beta gamma and PH domain-containing proteins may play a significant role in cellular signaling analogous to that previously demonstrated for Src homology 2 and 3 domains.
authors.affiliation: Howard Hughes Medical Research Institute, Department of Medicine, Duke 27710.
authors.forename: K
authors.initials: K
authors.lastname: Touhara
authors.forename: J
authors.initials: J
authors.lastname: Inglese
authors.forename: J A
authors.initials: JA
authors.lastname: Pitcher
authors.forename: G
authors.initials: G
authors.lastname: Shaw
authors.forename: R J
authors.initials: RJ
authors.lastname: Lefkowitz
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001798:Blood Proteins / Q000235:genetics / Q000378:metabolism*; D002417:Cattle; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D010750:Phosphoproteins; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D051552:beta-Adrenergic Receptor Kinases
chemical_list: D001798:Blood Proteins; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; C039077:platelet protein P47; D005982:Glutathione Transferase; D017868:Cyclic AMP-Dependent Protein Kinases; D051552:beta-Adrenergic Receptor Kinases; D019204:GTP-Binding Proteins