Wallace M A, Fain J N
J Biol Chem. 1985 Aug 15;260(17):9527-30.
The guanine nucleotide analogue, guanosine 5'-O-thiotriphosphate (GTP gamma S) stimulated plasma membrane-associated phospholipase C. Phosphoinositides were the substrates for the reaction. Significant losses of phosphatidylinositol bisphosphate and phosphatidylinositol phosphate occurred at lower doses of GTP gamma S than did significant loss of phosphatidylinositol. Loss of 32P-labeled phosphatidylinositol bisphosphate was equal when plasma membranes were treated with either 100 microM GTP or 100 microM GTP gamma S, but accumulation of inositol trisphosphate was more apparent when the nonhydrolyzable analogue was used. The action of GTP gamma S alone was not dependent on Ca2+ although loss of 32P-labeled phosphoinositides was stimulated by Ca2+ alone or with GTP gamma S. The results are consistent with a role for guanine nucleotide binding proteins in the activation of membrane-bound phosphoinositide-specific phospholipase C.
鸟嘌呤核苷酸类似物，鸟苷5'-O-硫代三磷酸（GTPγS）刺激了与质膜相关的磷脂酶C。磷酸肌醇是该反应的底物。与磷脂酰肌醇的显著损失相比，较低剂量的GTPγS就能导致磷脂酰肌醇二磷酸和磷脂酰肌醇磷酸的显著损失。当用100μM GTP或100μM GTPγS处理质膜时，32P标记的磷脂酰肌醇二磷酸的损失是相同的，但使用不可水解类似物时，肌醇三磷酸的积累更明显。单独的GTPγS的作用不依赖于Ca2+，尽管单独的Ca2+或与GTPγS一起能刺激32P标记的磷酸肌醇的损失。这些结果与鸟嘌呤核苷酸结合蛋白在激活膜结合的磷酸肌醇特异性磷脂酶C中的作用一致。
