情報伝達におけるGTP結合蛋白の役割に関する卵母細胞を用いた分子神経生物学的研究

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To Assign GTP-binding protein (G-protein) subtyps involved in the signal transduction from exogenous receptors to phospholipase C in the Xenopus oocyte translation system, antisense DNA complementary to rat G-protein alpha-subunit mRNA was designed and injected together with rat brain poly(A)^+mRNA. Current responses of mRNA-injected oocytes to acetylcholine (ACh) was suppressed by a co-injection of Gilalpha-antisense DNA dose-dependently, but response of the same oocytes to serotonin (5-HT) was not inhibited. In the oocytes co-injected with Goalpha-antisense DNA, the 5-HT response was more effectively suppressed than the ACh response. These result suggest that Goalpha but not Gilalpha intermediates brain 5-HTlc receptor function, and in contrast, muscarinic receptors derived from rat brain utilize Gilalpha rather than Goalpha to activate phospholipase C. Putative effects of G-protein on voltage-dependent calcium channels were also suggested.