Protein phosphorylation in nerve terminals: comparison of calcium/calmodulin-dependent and calcium/diacylglycerol-dependent systems-猫眼课题宝

神经末梢的蛋白质磷酸化：钙/钙调蛋白依赖性和钙/二酰甘油依赖性系统的比较

DOI：

发表时间：

1988

期刊：

Journal of Neuroscience

影响因子：

5.3

通讯作者：

中科院分区：

医学1区

文献类型：

作者：

J.K.T. Wang;S. Walaas;P. Greengard

已用 32P-正磷酸盐预先标记的大鼠大脑皮质突触体暴露于（1）K 去极化，导致 Ca2+ 流入，因此预计会激活 Ca2+ 依赖性酶，包括 Ca2+/钙调蛋白依赖性和 Ca2+/二酰基甘油依赖性蛋白激酶（分别为 Ca/CaM 激酶和蛋白激酶 C）； (2)佛波酯或1-油酰基-2-乙酰基-甘油(OAG)，其选择性地激活蛋白激酶C。磷酸化状态受这些处理影响的蛋白质可分为3类。 A 类包括 5 种磷蛋白，这些磷蛋白通过突触体去极化而不是通过 OAG 或佛波酯显示出快速增加的磷酸化。这些蛋白质中的四种，即突触蛋白 Ia 和 Ib 以及蛋白质 IIIa 和 IIIb，是神经元特异性的突触小泡相关蛋白质，已知是 Ca/CaM 激酶 I 和 II 的底物。这些磷蛋白在突触体复极化后迅速去磷酸化。 B 类由 2 种磷蛋白组成，通过突触体去极化或佛波酯或 OAG 处理，磷酸化迅速增加。从体外研究中已知 Mr87 和 49 kDa 这 2 个酸性蛋白是蛋白激酶 C 的特异性底物。热解肽图谱表明突触体中的 87 kDa 蛋白被蛋白激酶 C 原位磷酸化。这两种磷蛋白在突触体复极化时缓慢去磷酸化。 C 类包含 4 种磷蛋白，它们在突触体去极化时迅速去磷酸化，可能是 Ca2+ 激活的蛋白磷酸酶的底物。这些数据表明，Ca2+ 流入神经末梢会激活 Ca/CaM 激酶 I 和 II、蛋白激酶 C 和未识别的蛋白磷酸酶。

Rat cerebral cortical synaptosomes that had been prelabeled with 32P- orthophosphate were exposed to either (1) K depolarization which causes Ca2+ influx and hence would be expected to activate Ca2+-dependent enzymes, including Ca2+/calmodulin-dependent and Ca2+/diacylglycerol- dependent protein kinases (Ca/CaM kinases and protein kinase C, respectively); or (2) phorbol esters or 1-oleoyl-2-acetyl-glycerol (OAG), which selectively activate protein kinase C. Proteins whose state of phosphorylation was affected by these treatments could be divided into 3 classes. Class A includes 5 phosphoproteins that showed rapidly increased phosphorylation by synaptosomal depolarization but not by OAG or phorbol ester. Four of these proteins, synapsins Ia and Ib and proteins IIIa and IIIb, are neuron-specific, synaptic vesicle- associated proteins known to be substrates for Ca/CaM kinases I and II. These phosphoproteins were rapidly dephosphorylated upon synaptosomal repolarization. Class B is composed of 2 phosphoproteins that showed rapidly increased phosphorylation by either synaptosomal depolarization or treatment with phorbol ester or OAG. These 2 acidic proteins of Mr87 and 49 kDa are known from in vitro studies to be specific substrates for protein kinase C. Thermolytic peptide mapping indicated that the 87 kDa protein in synaptosomes was phosphorylated by protein kinase C in situ. These 2 phosphoproteins were slowly dephosphorylated upon synaptosomal repolarization. Class C comprises 4 phosphoproteins that were rapidly dephosphorylated upon synaptosomal depolarization and may be substrates for Ca2+-activated protein phosphatase(s). These data suggest that Ca2+ influx into nerve terminals activates Ca/CaM kinases I and II, protein kinase C, and unidentified protein phosphatase(s).