Inositol phospholipid metabolism in Xenopus oocytes mediated by endogenous Go and Gi proteins

Abstract

To characterize G‐proteins which mediate the signal transduction from ligand stimulated receptor to phospholipase C (PLC), we injected antisense DNAs complementary to Xenopus G_oα or G_i‐1α to suppress these endogenous G‐proteins, together with the mRNAs encoding metabotropic glutamate receptor 1 (mGluR1), 5 (mGluR5) or with M1 type muscarinic receptor into oocytes. Receptor‐stimulated chloride current responses were reduced by the suppression of Xenopus G_oα regardless of the types of receptors. However, injection of G_i‐1 antisense DNA resulted in the reduction of M1‐stimulated responses but not mGluR‐stimulated responses. These results suggested that all these receptors could use G_oα and M1 receptors, but not mGluRs, could also use G_i‐1 proteins, to activate PLC in Xenopus oocytes.