依赖钙离子的突触结合蛋白与SNAP-25的结合对于钙离子触发的胞吐作用至关重要。

Ca2+-dependent synaptotagmin binding to SNAP-25 is essential for Ca2+-triggered exocytosis.

作者信息

Zhang Xiaodong, Kim-Miller Mindy J, Fukuda Mitsunori, Kowalchyk Judith A, Martin Thomas F J

机构信息

Department of Biochemistry, University of Wisconsin, Madison 53706, USA.

出版信息

Neuron. 2002 May 16;34(4):599-611. doi: 10.1016/s0896-6273(02)00671-2.

DOI:10.1016/s0896-6273(02)00671-2

PMID:12062043

Abstract

Synaptotagmin is a proposed Ca2+ sensor on the vesicle for regulated exocytosis and exhibits Ca2+-dependent binding to phospholipids, syntaxin, and SNAP-25 in vitro, but the mechanism by which Ca2+ triggers membrane fusion is uncertain. Previous studies suggested that SNAP-25 plays a role in the Ca2+ regulation of secretion. We found that synaptotagmins I and IX associate with SNAP-25 during Ca2+-dependent exocytosis in PC12 cells, and we identified C-terminal amino acids in SNAP-25 (Asp179, Asp186, Asp193) that are required for Ca2+-dependent synaptotagmin binding. Replacement of SNAP-25 in PC12 cells with SNAP-25 containing C-terminal Asp mutations led to a loss-of-function in regulated exocytosis at the Ca2+-dependent fusion step. These results indicate that the Ca2+-dependent interaction of synaptotagmin with SNAP-25 is essential for the Ca2+-dependent triggering of membrane fusion.

摘要

突触结合蛋白是一种被认为存在于囊泡上用于调节性胞吐作用的钙离子传感器，在体外它表现出对磷脂、 syntaxin和SNAP - 25的钙离子依赖性结合，但钙离子触发膜融合的机制尚不清楚。先前的研究表明，SNAP - 25在钙离子对分泌的调节中起作用。我们发现，在PC12细胞的钙离子依赖性胞吐过程中，突触结合蛋白I和IX与SNAP - 25相互关联，并且我们确定了SNAP - 25中钙离子依赖性突触结合蛋白结合所必需的C末端氨基酸（Asp179、Asp186、Asp193）。用含有C末端天冬氨酸突变的SNAP - 25替换PC12细胞中的SNAP - 25，导致在钙离子依赖性融合步骤的调节性胞吐功能丧失。这些结果表明，突触结合蛋白与SNAP - 25的钙离子依赖性相互作用对于钙离子依赖性触发膜融合至关重要。