Kikkawa S, Takahashi K, Takahashi K, Shimada N, Ui M, Kimura N, Katada T
Department of Life Science, Tokyo Institute of Technology, Yokohama, Japan.
FEBS Lett. 1992 Jul 6;305(3):237-40. doi: 10.1016/0014-5793(92)80676-8.
We have previously reported that GDP-bound alpha beta gamma-trimeric GTP-binding (G) proteins can be converted into the active GTP-bound form with nucleoside diphosphate (NDP) kinase and ATP, although its exact activation mechanism still remains to be resolved. In the present study, we investigated whether NDP kinase activity was modified by mastoparan, a wasp venom peptide that is known to activate G proteins as an agonist-receptor complex. The activity of NDP kinase measured by the formation of GTP from ATP and GDP was markedly stimulated, when the kinase was incubated with mastoparan. The concentration of mastoparan required for the activation was much lower than that observed for the peptide-induced activation of G proteins under similar assay conditions. There was also an increase in the phosphorylated intermediate of NDP kinase as well as the catalytic activity upon its incubation with mastoparan. These results suggest that mastoparan not only activates G proteins directly via guanine nucleotide exchange reaction but also stimulates NDP kinase activity.
我们之前曾报道过，结合GDP的αβγ三聚体GTP结合（G）蛋白可以通过核苷二磷酸（NDP）激酶和ATP转化为活性GTP结合形式，尽管其确切的激活机制仍有待解决。在本研究中，我们研究了NDP激酶活性是否会被蜂毒肽修饰，蜂毒肽是一种黄蜂毒液肽，已知可作为激动剂 - 受体复合物激活G蛋白。当激酶与蜂毒肽一起孵育时，通过由ATP和GDP形成GTP来测量的NDP激酶活性受到显著刺激。在类似的测定条件下，激活所需的蜂毒肽浓度远低于肽诱导的G蛋白激活所观察到的浓度。当NDP激酶与蜂毒肽一起孵育时，其磷酸化中间体以及催化活性也有所增加。这些结果表明，蜂毒肽不仅通过鸟嘌呤核苷酸交换反应直接激活G蛋白，还刺激NDP激酶活性。
