CRYSTALLOGRAPHIC ANALYSIS OF SYNAPTOTAGMIN C2A-C2B

这个子项目是许多利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 突触结合蛋白1介导神经递质囊泡与神经元突触前末梢的Ca+2依赖性融合。 虽然有相当多的结构和生物化学信息的synaptotagmin分子，其确切的功能仍然不清楚，然而，大多数原子分辨率结构的结论是，两个串联的C2结构域的synaptotagmin的自主代理商连接一个小的连接器。 由于我们独特的纯化和结晶方法，我们已经捕获了人突触结合蛋白1 C2 A-C2B，其构象显示在Ca+2引发之前存在的结构域之间的接触。 到目前为止，我们在SSRL分析的晶体显示，参与Ca+2结合、磷脂结合和SNARE蛋白结合的C2 A区域被扭曲，并且可能通过与C2B的分子内相互作用而失活。 这些相互作用形成了一种触发机制，旨在响应变化的Ca+2浓度。 这些结论对于我们理解神经元的基本功能至关重要。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Synaptotagmin 1 mediates the Ca+2-dependent fusion of neurotransmitter-filled vesicles with the presynaptic terminus in neurons. While there is considerable structural and biochemical information on the synaptotagmin molecule, its precise function is still unclear; however, most atomic resolution structures conclude that the two tandem C2 domains of synaptotagmin were autonomous agents attached by a small linker. Due to our unique purification and crystallization method, we have captured human synaptotagmin 1 C2A-C2B in a conformation that shows contacts between domains as they exist prior to Ca+2 priming. The crystals we have analyzed at SSRL to this point reveal that areas of C2A involved in Ca+2 binding, phospholipid association and SNARE protein binding are distorted and probably inactivated through intra-molecular interactions with C2B. These interactions form a trigger mechanism designed to respond to changing Ca+2 concentrations. These conclusions will be essential to our understanding of fundamental neuronal function.