CRYSTAL STRUCTURE DETERMINATION OF YEAST GET3

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 尾锚式(Tail-Anchored，TA)蛋白是一类独特的跨膜蛋白家族，其C末端含有一个跨膜螺旋(约25个残基)。TA蛋白将TMD插入细胞膜的机制不同于研究较多的由胞浆信号识别颗粒(SRP)介导的共翻译插入途径。TA蛋白翻译后插入内质网需要高尔基体转运(GET)复合体，该复合体包含Get1、Get2和Get3。Get3是一种ATPase，可以识别和结合TA蛋白的C端跨膜区(TMD)。目前还不清楚Get复合体是如何完成TA蛋白的膜插入的。最近我们测定了酵母Get3开放构象的晶体结构。该结构提示Get3在无核苷酸状态下为开放构象，在ATP结合状态下为闭合构象。Get3在开放构象和闭合构象之间切换的构象变化可能有利于TA蛋白的膜插入。Get3可能与ABC转运蛋白具有类似的转移结合配体的机制。现在我们请求光束时间来确定闭合构象中的Get3晶体结构，以证实我们的假设。

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. Tail-anchored (TA) proteins represent a unique family of transmembrane proteins which contain a single transmembrane helix (about 25 residues) at the C-terminus. The mechanisms how the TA proteins insert the TMD into membranes are distinct from the well-studied co-translational insertion pathway, which is mediated by the cytosolic signal recognition particle (SRP). The post-translational insertion of the TA proteins into ER membrane requires the Golgi ER trafficking (GET) complex which contains Get1, Get2 and Get3. Get3 is an ATPase and can recognize and bind the C- terminal transmembrane domain (TMD) of the TA proteins. It is not well understood how GET complex accomplish the membrane insertion of the TA protein. Recently we have determined the yeast Get3 crystal structure in the open conformation. The structure suggested that Get3 may adopt an open conformation in nucleotide-free state and a closed conformation in ATP-bound state. The conformational changes to switch the Get3 between the open and closed conformations may facilitate the membrane insertions for TA proteins. Get3 may share a similar mechanism as the ABC transporters to transfer bound ligands. Now we are requesting beam time to determine Get3 crystal structure in the closed conformation to confirm our hypothesis.