Molecular composition of transmitter release site and the mechanism of synaptic vesicle tethering

最近的研究为阐明神经递质释放的分子机制铺平了道路。然而，许多方面的分子组成和突触囊泡拴系机制的释放网站仍然没有解决。在本研究中，我们首先研究了胞浆蛋白突触蛋白在释放机制中的作用机制。通过注射一种肽，构成突触蛋白结合位点的突触融合蛋白到鱿鱼巨大的突触前末端，我们已经表明，突触蛋白是必不可少的神经递质分子的快速释放。我们的研究结果表明，蛋白质的作用，促进寡聚化的陷阱复合物。突触蛋白可能在融合前发挥作用，mGluR7结合蛋白的研究仍在进行中。我们还没有成功地获得这些蛋白质的全长cDNA克隆。这些蛋白质的mRNA可能很容易降解。为了了解突触囊泡定位在神经末梢质膜内表面释放位点的机制，我们使用了果蝇幼虫的神经肌肉接头。我们的研究结果表明，不像储备池的突触囊泡，其中涉及突触囊泡蛋白synapsin，细胞骨架蛋白微管蛋白是很重要的形成容易释放池。免疫组织化学染色明确地证明了神经末梢中微管蛋白结构的动态运动。我们的研究结果表明，微管在神经末梢的重要作用。

Recent studies have paved the way for the elucidation of the molecular mechanisms of neurotransmitter release. However, many aspects of the molecular composition and synaptic vesicle tethering mechanisms of the release site remain unsolved. In this research, we first studied the mechanism of action of the cytosolic protein synaphin in the release mechanisms. By injecting a peptide that constitute the synaphin binding site to syntaxin into the squid giant presynaptic terminal, we have shown that synaphin is essential for the fast release of neurotransmitter molecules. Our results suggest that the protein act by facilitating oligomerization of SNARE complexes. Synaphin probably acts just before fusion.The study on mGluR7 binding proteins is still underway. We have not yet succeeded in obtaining full-length cDNA clones for these proteins. The mRNAs for these proteins are probably very liable to degradation.To understand the mechanisms for synaptic vesicle localization at the release site at the internal surface of the plasma membrane in the nerve terminal we have used the neuromuscular junction of Drosophila larva. Our findings indicate that unlike the reserve pool of synaptic vesicles which involves the synaptic vesicle protein synapsin, the cytoskeletal protein tubulin is important for the formation of the readily releasable pool. The dynamic movement of tubulin structures in the nerve terminal was unambiguously demonstrated by immunohistochemical staining. Our results suggest an important role for microtubules in the nerve terminal.