CRYSTALLOGRAPHIC STUDIES OF GI1-ALPHA MUTANTS

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。 异三聚体鸟嘌呤核苷酸结合调节蛋白G蛋白将信号从七螺旋跨膜G蛋白偶联受体(GPCRs)传递到细胞内部。GPCRs通过诱导激活的受体-蛋白质复合体中的G？亚基释放GDP来激活G蛋白。尽管各种G？亚基的晶体结构有很多报道，但对于G？亚基通过受体激活核苷酸交换的机制，我们仍然缺乏详细的了解。我们的项目旨在阐明G蛋白激活途径中的瞬时步骤。我们的总体策略是获得我们在体外和基于细胞的分析中表征的G蛋白突变体的晶体结构。特别是，我们已经确定并表征了一类有趣的突变G蛋白α亚单位，具有极高的GDP基础释放率。这些研究对于理解各种GPCR靶向药物的作用机制非常重要，并将帮助我们更多地从结构上深入了解G蛋白信号通路。

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. Heterotrimeric guanine nucleotide-binding regulatory proteins, G proteins relay signals from heptahelical transmembrane G protein coupled receptors (GPCRs) to the cellular interior. GPCRs activate G proteins by inducing the release of GDP from the G¿ subunit in the activated receptor-protein complex. Despite reports of many crystals structures of various G¿ subunits, we still lack a detailed understanding of the mechanism of receptor activated nucleotide exchange by the G¿ subunit. Our project is aimed at elucidating transient steps in the G protein activation pathway. Our general strategy is to obtain crystal structures of G protein mutants that we characterized in vitro and in cell-based assays. In particular, we have identified and characterized an interesting class of mutant G protein alpha subunits with extremely high basal rates of GDP release. These studies are very important to understanding the mechanism of action of various GPCR-targeted drugs and will help us to gain more structural insights into G protein signaling pathways in general.