Wang J K, Walaas S I, Sihra T S, Aderem A, Greengard P
Laboratory of Molecular and Cellular Neuroscience, Rockefeller University, New York, NY 10021.
Proc Natl Acad Sci U S A. 1989 Apr;86(7):2253-6. doi: 10.1073/pnas.86.7.2253.
A protein of 87 kilodaltons (87 kDa) was previously identified as a major specific substrate for protein kinase C in neuronal and other tissues. We have now studied the effect of protein kinase C-catalyzed phosphorylation of this protein on its association with membranes in isolated nerve terminals (synaptosomes) from rat cerebral cortex. Incubation of synaptosomal membranes under conditions associated with activation of protein kinase C led to the release of the phosphorylated 87-kDa protein into the incubation medium. In intact synaptosomes, activation of protein kinase C by phorbol esters or by depolarization-induced Ca2+ influx caused an increased phosphorylation of the 87-kDa protein and its translocation from membrane to cytosol. This translocation showed time courses, calcium dependency, and reversibility similar to those observed for the protein kinase C-induced phosphorylation of the protein. These results suggest that protein kinase C-catalyzed phosphorylation of the 87-kDa protein is responsible for its subcellular translocation into the cytosol of nerve terminals.
一种87千道尔顿（87 kDa）的蛋白质先前被鉴定为神经元和其他组织中蛋白激酶C的主要特异性底物。我们现在研究了蛋白激酶C催化该蛋白质磷酸化对其与大鼠大脑皮层分离神经末梢（突触体）中膜的结合的影响。在与蛋白激酶C激活相关的条件下孵育突触体膜，导致磷酸化的87 kDa蛋白质释放到孵育培养基中。在完整的突触体中，佛波酯或去极化诱导的Ca2+内流激活蛋白激酶C会导致87 kDa蛋白质的磷酸化增加，并使其从膜转移到细胞质中。这种转移显示出与蛋白激酶C诱导的该蛋白质磷酸化相似的时间进程、钙依赖性和可逆性。这些结果表明，蛋白激酶C催化的87 kDa蛋白质磷酸化是其亚细胞转移到神经末梢细胞质中的原因。
