SYNAPTOBREVIN BINDING TO SYNAPTOPHYSIN - A POTENTIAL MECHANISM FOR CONTROLLING THE EXOCYTOTIC FUSION MACHINE
SYNAPTOBREVIN BINDING TO SYNAPTOPHYSIN - A POTENTIAL MECHANISM FOR CONTROLLING THE EXOCYTOTIC FUSION MACHINE
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DOI：
10.1002/j.1460-2075.1995.tb06995.x
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发表时间：
1995-01-16
期刊：
影响因子：
11.4
通讯作者：
JAHN, R
中科院分区：
文献类型：
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作者：
EDELMANN, L;HANSON, PI;JAHN, R
突触泡蛋白（synaptic ves泡protein synaptobrevin， VAMP）最近被认为是参与胞外膜融合的关键蛋白之一。它与突触膜蛋白syntaxin I和突触体相关蛋白（synaptosome-associated protein， SNAP）-25相互作用，形成胞外分泌前的复合物[Sollner et al . (1993b) Cell, 75, 409-418]。在这里，我们证明了大多数的突触brevin是结合到囊泡蛋白synaptophysin在洗涤剂提取物。当使用突触素特异性抗体进行免疫沉淀时，在该复合体中未发现syntaxin I。相反，当使用syntaxin特异性抗体进行免疫沉淀时，没有synaptophysin与synaptobrevin-syntaxin I复合物相关。因此，与synaptophysin结合的synaptobrevin池无法与syntaxin I和SNAP-25结合，反之亦然。Synaptobrevin - synaptophysin的结合也通过化学交联在离体神经末梢得到证实。此外，重组synaptobrevin II能有效结合synaptophysin及其同工异构体synaptoporin，但不能结合更接近的突触囊泡蛋白p29。重组synaptobrevin I具有相似的结合效率，而非神经元异构体cellubrevin对synaptophysin的亲和力较低。高浓度NaCl处理导致突触蛋白-突触素复合物解离。此外，低剂量的SDS不可逆地消除了synaptobrevin与synaptophysin的相互作用，而增强了与syntaxin I的相互作用。我们得出结论，synaptophysin选择性地与synaptobrevin在一个复合物中相互作用，该复合物排除了t-SNAP受体syntaxin I和SNAP-25，这表明synaptophysin在胞吐的控制中起作用。
The synaptic vesicle protein synaptobrevin (VAMP) has recently been implicated as one of the key proteins involved in exocytotic membrane fusion. It interacts with the synaptic membrane proteins syntaxin I and synaptosome-associated protein (SNAP)-25 to form a complex which precedes exocytosis [Sollner et al, (1993b) Cell, 75, 409-418]. Here we demonstrate that the majority of synaptobrevin is bound to the vesicle protein synaptophysin in detergent extracts. No syntaxin I was found in this complex when synaptophysin-specific antibodies were used for immunoprecipitation. Conversely, no synaptophysin was associated with the synaptobrevin-syntaxin I complex when syntaxin-specific antibodies were used for immunoprecipitation. Thus, the synaptobrevin pool bound to synaptophysin is not available for binding to syntaxin I and SNAP-25, and vice versa. Synaptobrevin - synaptophysin binding was also demonstrated by chemical cross-linking in isolated nerve terminals. Furthermore, recombinant synaptobrevin II efficiently bound synaptophysin and its isoform synaptoporin, but not the more distantly related synaptic vesicle protein p29. Recombinant synaptobrevin I bound with similar efficiency, whereas the non-neuronal isoform cellubrevin displayed a lower affinity towards synaptophysin. Treatment with high NaCl concentrations resulted in a dissociation of the synaptobrevin - synaptophysin complex. In addition, the interaction of synaptobrevin with synaptophysin was irreversibly abolished by low amounts of SDS, while the interaction with syntaxin I was enhanced. We conclude that synaptophysin selectively interacts with synaptobrevin in a complex which excludes the t-SNAP receptors syntaxin I and SNAP-25, suggesting a role for synaptophysin in the control of exocytosis.