The t-SNAREs syntaxin 1 and SNAP-25 are present on organelles that participate in synaptic vesicle recycling.
The t-SNAREs syntaxin 1 and SNAP-25 are present on organelles that participate in synaptic vesicle recycling.
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DOI：
10.1083/jcb.128.4.637
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发表时间：
1995-02
期刊：
影响因子：
--
通讯作者：
Jahn R
中科院分区：
文献类型：
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作者：
Walch-Solimena C;Blasi J;Edelmann L;Chapman ER;von Mollard GF;Jahn R
突触融合蛋白1（Syntaxin 1）和25 kD的突触体相关蛋白（SNAP-25）是神经元质膜蛋白，在突触囊泡（SV）的胞吐过程中起重要作用。这两种蛋白质与小突触泡蛋白形成复合物，小突触泡蛋白是SV的内在膜蛋白。这种结合被认为是负责囊泡对接，显然先于膜融合。根据目前的概念，突触融合蛋白1和SNAP-25是更大的蛋白质家族的成员，统称为靶SNAP受体（t-SNARE），其特异性定位于亚细胞膜，定义了运输囊泡结合和融合的位置。在这里，我们证明了syntaxin 1和SNAP-25的主要池与SV循环。这两种蛋白质cofraculate与SV和网格蛋白包被的囊泡后，亚细胞分级。使用重组蛋白作为定量的标准，我们发现，syntaxin 1和SNAP-25各占高度纯化的SV中总蛋白的约3%。因此，这两种蛋白质都是SV的重要组分，尽管其丰度低于小突触泡蛋白（占总蛋白质的8.7%）。使用突触体蛋白和突触融合蛋白特异性抗体的囊泡的免疫分离显示，大多数SV含有突触融合蛋白1。免疫金电子显微镜进一步证实了突触融合蛋白1和SNAP-25在SV上的广泛分布。肉毒杆菌神经毒素C1，一种通过蛋白水解突触融合蛋白1来阻断胞吐作用的毒素，优先切割囊泡突触融合蛋白1。我们的结论是，t-SNARE参与SV回收的功能可能是不同的形式。
Syntaxin 1 and synaptosome-associated protein of 25 kD (SNAP-25) are neuronal plasmalemma proteins that appear to be essential for exocytosis of synaptic vesicles (SVs). Both proteins form a complex with synaptobrevin, an intrinsic membrane protein of SVs. This binding is thought to be responsible for vesicle docking and apparently precedes membrane fusion. According to the current concept, syntaxin 1 and SNAP-25 are members of larger protein families, collectively designated as target-SNAP receptors (t-SNAREs), whose specific localization to subcellular membranes define where transport vesicles bind and fuse. Here we demonstrate that major pools of syntaxin 1 and SNAP-25 recycle with SVs. Both proteins cofractionate with SVs and clathrin-coated vesicles upon subcellular fractionation. Using recombinant proteins as standards for quantitation, we found that syntaxin 1 and SNAP-25 each comprise approximately 3% of the total protein in highly purified SVs. Thus, both proteins are significant components of SVs although less abundant than synaptobrevin (8.7% of the total protein). Immunoisolation of vesicles using synaptophysin and syntaxin specific antibodies revealed that most SVs contain syntaxin 1. The widespread distribution of both syntaxin 1 and SNAP-25 on SVs was further confirmed by immunogold electron microscopy. Botulinum neurotoxin C1, a toxin that blocks exocytosis by proteolyzing syntaxin 1, preferentially cleaves vesicular syntaxin 1. We conclude that t- SNAREs participate in SV recycling in what may be functionally distinct forms.