Syntaxin-1是特异性地分布在神经细胞突触前质膜上的蛋白。它早期被作为分子量为35 kD的synaptotagmin-1结合蛋白,但很快就被认识到是细胞质膜融合的关键蛋白。Syntaxin-1通过与SNAP25和Synaptobrevin/VAMP蛋白聚合,进而形成被认为是神经突触囊泡融合必要因子的SNARE核心复合体。作为一个多结构域的蛋白,syntaxin-1与多个突触蛋白相互作用,其作用远超出了仅作为SNARE核心复合体中一个蛋白质成员的作用。本文着重介绍了有关syntaxin-1与其它SNARE组份蛋白、munc18蛋白和钙离子通道的相互作用及其功能的最新研究进展。全面揭示syntaxin-1作为SNARE核心复合体成员的功能以及超越这一功能的作用,还有待于对其结构以及与其它突触蛋白相互作用特性的进一步深刻理解。
Syntaxin-1 was initially identified as a neuronal protein of unknown function,but soon shown to bind to synaptotagmin and calcium channels and thus recognized as a key component of the synaptic vesicle fusion machinery.Syntaxin-1 is a SNARE protein that assembles with the SNARE proteins SNAP-25 and synaptobrevin/VAMP into SNARE complexes;SNARE-complex assembly is an endergonic process that fuels vesicle fusion,which in turn is catalyzed by the SM protein Munc18-1.Different from SNAP-25 and synaptobrevin,syntaxin-1 is a multi-domain protein that does more than form SNARE complexes ——its various domains orchestrate SNARE-complex assembly,bind regulators such as complexins and synaptotagmins,and contribute to controlling calcium channels that are located in close proximity to the sites of vesicle fusion.This review highlights the updated evidence that describes the interactions of syntaxin-1 with other SNARE proteins,Munc18,synaptotagmin,complexin,and calcium channels.These interactions provide a probable explanation for the central role of syntaxin-1 in vesicle fusion,but how precisely syntaxin-1 performs this role still remains an enigma.Solving this enigma will require in-depth a better understanding of what steps in fusion are exactly controlled by syntaxin-1,and how the different domains and conformational states of syntaxin-1 effect this control.