title: Socius, a novel binding partner of Galpha12/13, promotes the Galpha12-induced RhoA activation.
abstract: Heterotrimeric G proteins act as a molecular switch that conveys signals from G protein-coupled receptors in the cell membrane to intracellular downstream effectors. The Galpha subunits of the G(12) family of heterotrimeric G proteins, defined by Galpha(12) and Galpha(13), have many cellular functions through their specific downstream effectors. On the other hand, regulatory systems of the activity of Galpha(12) and Galpha(13) have not been fully clear. Here, we show that Socius, a previously identified Rho family small GTPase Rnd1 interacting protein, binds directly to Galpha(12) and Galpha(13) through its NH(2)-terminal region. Socius increased the amounts of GTP-bound active form of Galpha(12) in 293T cells. Furthermore, Socius promotes the Galpha(12)-induced RhoA activation in 293T cells. These results demonstrate that Socius is a novel activator of the Galpha(12) family.
authors.affiliation: Laboratory of Molecular Neurobiology, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Japan.
authors.forename: Katsunori
authors.initials: K
authors.lastname: Tateiwa
authors.forename: Hironori
authors.initials: H
authors.lastname: Katoh
authors.forename: Manabu
authors.initials: M
authors.lastname: Negishi
mesh_terms: D002460:Cell Line; D004789:Enzyme Activation; D044365:GTP-Binding Protein alpha Subunits, G12-G13 / Q000378:metabolism*; D006801:Humans; D008024:Ligands; D011485:Protein Binding; D011956:Receptors, Cell Surface / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
chemical_list: D008024:Ligands; D011956:Receptors, Cell Surface; D044365:GTP-Binding Protein alpha Subunits, G12-G13; D020742:rhoA GTP-Binding Protein