Inositol phospholipid metabolism in Xenopusoocytes mediated by endogenous Goand Giproteins

To characterize G‐proteins which mediate the signal transduction from ligand stimulated receptor to phospholipase C (PLC), we injected antisense DNAs complementary to XenopusGoα or Gi‐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 XenopusGoα regardless of the types of receptors. However, injection of Gi‐1antisense DNA resulted in the reduction of M1‐stimulated responses but not mGluR‐stimulated responses. These results suggested that all these receptors could use Goα and M1 receptors, but not mGluRs, could also use Gi‐1proteins, to activate PLC in Xenopusoocytes.