CA2+ REGULATES THE INTERACTION BETWEEN SYNAPTOTAGMIN AND SYNTAXIN-1
CA2+ REGULATES THE INTERACTION BETWEEN SYNAPTOTAGMIN AND SYNTAXIN-1
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DOI：
10.1074/jbc.270.40.23667
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发表时间：
1995-10-06
影响因子：
4.8
通讯作者：
JAHN, R
中科院分区：
文献类型：
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作者：
CHAPMAN, ER;HANSON, PI;JAHN, R
虽然有令人信服的证据表明，突触囊泡蛋白synaptotagmin作为主要的Ca 2+传感器调节胞吐，它是不知道如何Ca 2+结合启动膜融合。在这里，我们报告说，钙离子增加的亲和力，约2个数量级，突触结合蛋白和突触融合蛋白1，突触融合器的组成部分之间。这种效应对于可以刺激突触囊泡的胞吐作用的二价阳离子是特异性的（Ca 2 + > Ba 2+，Sr 2 + >> Mg 2+）。的Ca 2+依赖的相互作用是由两个组件的EC（50）值为0.7和180 μ M的Ca 2+。这种相互作用是由突触融合蛋白1的羧基末端区域（残基194-288）介导的，并且由一个新的Ca 2+结合位点调节，该位点不需要磷脂，并且不被消除Ca 2+依赖性磷脂与突触结合蛋白结合的突变破坏。我们建议，这种相互作用构成了兴奋分泌耦合的一个重要步骤。
While there is compelling evidence that the synaptic vesicle protein synaptotagmin serves as the major Ca2+ sensor for regulated exocytosis, it is not known how Ca2+ binding initiates membrane fusion. Here we report that Ca2+ increases the affinity, by approximately 2 orders of magnitude, between synaptotagmin and syntaxin 1, a component of the synaptic fusion apparatus. This effect is specific for divalent cations which can stimulate exocytosis of synaptic vesicles (Ca2+ > Ba2+, Sr2+ >> Mg2+). The Ca2+- dependence of the interaction was composed of two components with EC(50) values of 0.7 and 180 mu M Ca2+. The interaction is mediated by the carboxyl-terminal region of syntaxin 1 (residues 194-288) and is regulated by a novel Ca2+-binding site(s) which does not require phospholipids and is not disrupted by mutations that abolish Ca2+-dependent phospholipid binding to synaptotagmin. We propose that this interaction constitutes an essential step in excitation-secretion coupling.