Wolf M, LeVine H, May W S, Cuatrecasas P, Sahyoun N
Nature. 1985;317(6037):546-9. doi: 10.1038/317546a0.
The activation of protein kinase C by diacylglycerol and by tumour promoters has implicated this enzyme in transmembrane signalling and in the regulation of the cell cycle. In vitro studies revealed that catalytic activity requires the presence of calcium and phospholipids with a preference for phosphatidylserine. Diacylglycerol and tumour promoters such as phorbol esters bind to the enzyme, leading to its activation while sharply increasing its affinity for Ca2+ and phospholipid. Addition of diacylglycerol analogues or phorbol esters to intact cells results in the phosphorylation of specific polypeptides. Several cellular processes, including hormone and neurotransmitter release and receptor down-regulation, are modulated by the activation of protein kinase C, while phorbol ester-induced stimulation of the enzyme in whole cells has been associated with its translocation from the cytoplasm to the plasma membrane. Moreover, the use of Ca2+ ionophores has revealed an apparent synergism between Ca2+ mobilization and protein kinase C activation. This synergism has recently also been found to apply to receptor down-regulation (ref. 23 and accompanying paper). Here we describe a reconstitution system in which intracellular translocation of protein kinase C and the synergism between Ca2+ and enzyme activators can be studied. The results suggest a rationale for concomitant Ca2+ mobilization and diacylglycerol formation in response to some hormones, neurotransmitters and growth factors.
二酰基甘油和肿瘤启动子对蛋白激酶C的激活作用表明，该酶参与跨膜信号传导和细胞周期调控。体外研究表明，催化活性需要钙和磷脂的存在，且对磷脂酰丝氨酸有偏好。二酰基甘油和肿瘤启动子如佛波酯与该酶结合，导致其激活，同时大幅增加其对Ca2+和磷脂的亲和力。向完整细胞中添加二酰基甘油类似物或佛波酯会导致特定多肽的磷酸化。包括激素和神经递质释放以及受体下调在内的几种细胞过程受到蛋白激酶C激活的调节，而佛波酯在全细胞中对该酶的诱导刺激与其从细胞质向质膜的转位有关。此外，使用Ca2+离子载体已揭示Ca2+动员与蛋白激酶C激活之间存在明显的协同作用。最近还发现这种协同作用也适用于受体下调（参考文献23及相关论文）。在此，我们描述了一种重组系统，可用于研究蛋白激酶C的细胞内转位以及Ca2+与酶激活剂之间的协同作用。结果为响应某些激素、神经递质和生长因子时伴随的Ca2+动员和二酰基甘油形成提供了一种理论依据。
