Structure of the Rhodopsin/Transducin Complex

描述(由申请人提供)： G蛋白偶联受体(GPCRs)是一个完整的膜蛋白超家族，通过G蛋白向下游效应器传递信号。关于GPCRs如何激活它们各自的G蛋白的详细分子信息往往是缺乏的。视紫红质是视网膜中的一种光感受器，定义了最大的GPCRs亚家族。因此，它可以作为其他受体的范例。视紫红质与转导蛋白(它的G蛋白)的偶联能力的异常与疾病有关。本文提出的研究将提供有关视紫红质/转导蛋白复合体的直接结构信息。视紫红质和转导蛋白(GT)的定点自旋标记(SDSL)实验将揭示由于它们相互作用而发生构象变化的区域。这项建议的一个目标是确定转导蛋白中对GDP释放重要的构象变化区域。对这些结构变化的详细分析有望为GT内视紫红质催化的核苷酸交换提供一个机制模型。此外，还将进行距离测量，以绘制转导蛋白在视紫红质上的结合位置。总的来说，这些实验将提供有关视紫红质/转导蛋白复合体的详细结构信息。

DESCRIPTION (provided by applicant): G-protein coupled receptors (GPCRs) are a large superfamily of integral membrane proteins that transfer signals, via G-proteins, to downstream effectors. Detailed molecular information about how GPCRs activate their respective G-proteins is often lacking. Rhodopsin, a photoreceptor in the retina, defines the largest subfamily of GPCRs. As such, it acts as a paradigm for other receptors. Aberrations in rhodopsin's ability to couple to transducin (its G-protein) have been implicated in disease. The studies proposed here will provide direct structural information about the rhodopsin/transducin complex. Site-directed spin labeling (SDSL) experiments on both rhodopsin and transducin (Gt) will reveal regions of conformational change due to their mutual interaction. It is one goal of this proposal to identify areas of conformational change within transducin that are important for GDP release. Detailed analysis of these structural changes is expected to provide a mechanistic model for the rhodopsin catalyzed nucleotide exchange within Gt. Additionally, distance measurements will be made to map the binding site of transducin on rhodopsin. Collectively, these experiments will provide detailed structural information about the rhodopsin/transducin complex.