Cysteine residues of SNAP-25 are required for SNARE disassembly and exocytosis, but not for membrane targeting.
Cysteine residues of SNAP-25 are required for SNARE disassembly and exocytosis, but not for membrane targeting.
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SNARE 分解和胞吐作用需要 SNAP-25 的半胱氨酸残基，但膜靶向不需要。
DOI：
10.1042/0264-6021:3570625
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
Wilson,MC
中科院分区：
文献类型：
--
作者：
Washbourne,P;Cansino,V;Mathews,JR;Graham,M;Burgoyne,RD;Wilson,MC
神经递质在突触处的释放经由突触囊泡与质膜的调节融合而发生。两个脂质双层的融合由蛋白质复合物介导，所述蛋白质复合物包括质膜靶可溶性N-乙基马来酰亚胺敏感性融合蛋白（NSF）附着蛋白（SNAP）受体（t-SNARE）、突触融合蛋白1A和25 kDa的突触体相关蛋白（SNAP-25）以及囊泡SNARE（v-SNARE）、囊泡相关膜蛋白（VAMP）。虽然syntaxin 1A和VAMP通过C-末端跨膜结构域连接到膜上，但SNAP-25已经被认为通过四个棕榈酰化半胱氨酸残基锚定到膜上。我们证明，SNAP-25的半胱氨酸残基是不需要的膜定位时，syntaxin 1A的存在。由缺乏半胱氨酸残基的突变体形成的7S和20 S复合物的分析表明，半胱氨酸是有效的SNARE复合物解离所需的。此外，这些突变体不能支持胞吐，如通过PC 12细胞分泌测定所证明的。我们假设，syntaxin 1A用于指导新合成的SNAP-25通过高尔基体运输途径的轴突和突触，半胱氨酸残基的棕榈酰化是不需要的靶向，但优化SNARE复合物解离所需的相互作用。
The release of neurotransmitter at a synapse occurs via the regulated fusion of synaptic vesicles with the plasma membrane. The fusion of the two lipid bilayers is mediated by a protein complex that includes the plasma membrane target solubleN-ethylmaleimide-sensitive fusion protein (NSF) attachment protein (SNAP) receptors (t-SNAREs), syntaxin 1A and synaptosome-associated protein of 25kDa (SNAP-25), and the vesicle SNARE (v-SNARE), vesicle-associated membrane protein (VAMP). Whereas syntaxin 1A and VAMP are tethered to the membrane by a C-terminal transmembrane domain, SNAP-25 has been suggested to be anchored to the membrane via four palmitoylated cysteine residues. We demonstrate that the cysteine residues of SNAP-25 are not required for membrane localization when syntaxin 1A is present. Analysis of the 7S and 20S complexes formed by mutants that lack cysteine residues demonstrates that the cysteines are required for efficient SNARE complex dissociation. Furthermore, these mutants are unable to support exocytosis, as demonstrated by a PC12 cell secretion assay. We hypothesize that syntaxin 1A serves to direct newly synthesized SNAP-25 through the Golgi transport pathway to the axons and synapses, and that palmitoylation of cysteine residues is not required for targeting, but to optimize interactions required for SNARE complex dissociation.