Role of the cytoplasmic protein synaphin in the process of transmitter release

细胞质蛋白突触蛋白在递质释放过程中的作用

基本信息

批准号：
09680760
负责人：
ABE Teruo
金额：
$ 2.3万
依托单位：
Niigata University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09680760/
关键词：
Synaphin Transmitter release Syntaxin Synapse シナプスシナ-フィン

项目摘要

Synaphin is a cytosolic protein we first found to be associated with the docking/fusion complex that is critical to transmitter release. The goal of this study was to clarify the function of this protein in the release process. We have obtained following results.(1) Distribution in the brain and tevolutionary conservationTwo isoforms of synaphin (synaphins 1 and 2 : 84% identical) exist in the brain. The two isoforms are distictly distributed in the brain regions such as cerebral cortex, thalamus, cerebellum and amygdaloid., indicating different physiological implications for the isoforms. Synaphins very similar to mammalian ones are present in fish, and an invertebrate nervous system also contains the proteins.(2) FunctionWhen a peptide corresponding to a partial amino acid sequence of synaphin was injected into the presynaptic terminal of the squid giant synapse, transmitter release was rapidly inhibited. This peptide inhibited binding of synaphin to syntaxin but did not affect SNARE interactions, synaptic vesicle docking or calcium channel functions. Thus synaphin/syntaxin interaction is essential for transmitter release. In vitro binding experiments between recombinant SNARE proteins and synaphin show that syntaxin alone binds very little synaphin. However, the synaptic vesicle protein VAMP (synaptobrevin) markedly facilitated syntaxin binding to synaphin. Conversely, synaphin geatly increased the affinity of VAMP to syntaxin. Taken together, these results indicate that synaphin/SNARE interactions play an essential role at a step between synaptic vesicle docking and fusion.

突触蛋白是我们首先发现的一种胞质蛋白，与对递质释放至关重要的对接/融合复合物相关。本研究的目的是阐明该蛋白质在释放过程中的功能。我们得到了以下结果：(1)大脑中的分布和进化保守性突触蛋白的两种异构体(突触蛋白1和2：84％相同)存在于大脑中。这两种异构体明显分布在大脑皮层、丘脑、小脑和杏仁核等大脑区域，表明这两种异构体具有不同的生理意义。鱼类中存在与哺乳动物非常相似的突触蛋白，无脊椎动物的神经系统也含有这种蛋白质。 (2)功能当将与突触蛋白部分氨基酸序列相对应的肽注射到鱿鱼巨突触的突触前末端时，会释放递质被迅速抑制。该肽抑制突触蛋白与突触融合蛋白的结合，但不影响 SNARE 相互作用、突触小泡对接或钙通道功能。因此，突触蛋白/突触蛋白相互作用对于递质释放至关重要。重组 SNARE 蛋白和突触蛋白之间的体外结合实验表明，突触蛋白单独结合的突触蛋白非常少。然而，突触小泡蛋白 VAMP（synaptobrevin）显着促进突触蛋白与突触蛋白的结合。相反，突触蛋白极大地增加了 VAMP 与突触融合蛋白的亲和力。综上所述，这些结果表明突触蛋白/SNARE 相互作用在突触小泡对接和融合之间的步骤中发挥着重要作用。