The G-protein G13 but not G12 mediates signaling from lysophosphatidic acid receptor via epidermal growth factor receptor to Rho.

Lysophosphatidic acid (LPA) utilizes a G-protein-coupled receptor to activate the small GTP-binding protein Rho and to induce rapid remodeling of the actin cytoskeleton. We studied the signal transduction from LPA receptors to Rho activation. Analysis of the G-protein-coupling pattern of LPA receptors by labeling activated G-proteins with [alpha-32P]GTP azidoanilide revealed interaction with proteins of the Gq, Gi, and G12 subfamilies.

Receptors couple to L-type calcium channels via distinct Go proteins in rat neuroendocrine cell lines.

1. The present study examines the hypothesis of G protein subtype selectivity in receptor-induced inhibition of calcium channel currents (ICa) in the insulin-secreting RINm5F and pituitary GH3 rat cell lines. Specificity of receptor coupling to G proteins was studied by infusion of purified G alpha isoforms into cells via a patch pipette.

Interaction of G protein Gbetagamma dimers with small GTP-binding proteins of the Rho family.

Gbetagamma dimers of heterotrimeric G proteins have been shown to be important for the translocation of cytosolic proteins to membranes. The involvement of Gbetagamma in those signaling processes mediated by small GTP-binding proteins of the Rho family was studied using purified proteins. We showed specific binding of bovine brain Gbetagamma to immobilized GST-Rho fusion proteins.

Direct activation of trpl cation channels by G alpha11 subunits.

G proteins of the Gq/11 subfamily functionally couple cell surface receptors to phospholipase C beta (PLC beta) isoforms. Stimulation of PLC beta induces Ca2+ elevation by inositol 1,4,5-trisphosphate (InsP3)-mediated Ca2+ release and store-dependent 'capacitative' Ca2+ entry through Ca(2+)-permeable channels. The Drosophila trp gene, as well as some human trp homologs, code for such store-operated channels.

Distinct biochemical properties of the native members of the G12 G-protein subfamily. Characterization of G alpha 12 purified from rat brain.

G12 and G13 are insufficiently characterized pertussis toxin-insensitive G-proteins. Here, we describe the isolation of G alpha 12 from rat brain membranes. G alpha 12 was purified to apparent homogeneity by three steps of conventional chromatography, followed by two cycles of subunit-exchange chromatography on immobilized G subunits.