MEMBRANE TRANSPORTERS

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。这是一种来自大肠杆菌的“MFS-家族”膜蛋白，它以化学计量的方式与精氨酸交换其脱羧基产物--胍丁胺。在极端的耐酸反应中，它就像一个“虚拟的质子泵”。这种蛋白质很容易过度表达和结晶，我们目前正在努力提高晶体质量，以便能够开始认真的指数化和阶段划分。在过去的一年里，在最好的、各向同性的情况下，我们已经将衍射极限从大约20A提高到6A。我们的NSLS之旅是为了在这一点上进行筛选和优化。这在我们自己的光源上是做不到的，因为这些膜蛋白晶体需要高强度的光束来评估它们的衍射极限。如果我们能实现3.5A的各向同性衍射，我们就会开始分相，最初使用MAD和Semet导数，我们可以很容易地表达出来。

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. This is a "MFS-family" membrane protein from E coli that stoichiometircally exchanges arginine for its decarboxylation product, agmatine. It operates as a "virtual proton pump" in the extreme acid resistance response. This protein can be easily overexpressed and crystallized, and we are currently trying to improve crystal quality to the point where we can begin serious indexing and phasing. During the past year, we have improved diffraction limit from about 20 A to 6A in the best, isotropic cases. Our trips to NSLS are used for screenng and optimization at this point. This cannot be done on our home source, as these membrane protein crystals require a high-intensity beam to assess their diffration limit. If we can achieve isotropic diffraction out to 3.5 A, we will then begin phasing, initially using MAD with SeMet derivatives, which we can readily express.