STRUCTURE OF ACTIVE G PROTEIN COUPLED RECEPTORS

G蛋白偶联受体在心血管、内分泌和神经信号的细胞通讯以及细胞生长和分化中发挥关键作用。与G蛋白偶联受体激活相关的特定构象变化在分子水平上知之甚少。在少数人类疾病中已经发现了导致构成激活的这些受体的突变，这种机制很可能在其他更常见的疾病中起作用。在分子水平上，这些组成激活突变为更好地理解受体激活提供了一套强大的工具。我们对细胞通讯的分子机制的理解的一个主要差距源于高分辨率膜蛋白结构的缺乏。近年来，固态核磁共振作为一种获得膜蛋白高分辨率结构信息的有力方法而出现。我们建议通过固态核磁共振来检测细菌表达的15N标记受体片段的结构，这些片段包含跨膜结构域和关键的G蛋白激活结构。组成性激活突变对跨膜和细胞质结构的移动性和取向的影响将被确定，从而开始建立G蛋白激活的分子基础。

G protein coupled receptors play a key role in cellular communication in cardiovascular, endocrine, and neural signaling as well as in cell growth and differentiation. The specific conformational changes associated with activation of G protein coupled receptors are poorly understood at a molecular level. Mutations in these receptors which lead to constitutive activation have been identified in a small number of human diseases and it is likely that this mechanism is at play in other more common disorders. At a molecular level these constitutively activating mutations provide a set of powerful tools to better understand receptor activation. A major gap in our understanding of the molecular mechanisms of cellular communication derives from the paucity of high resolution membrane protein structures. Solid-state NMR has emerged recently as a powerful approach to obtain high resolution structural information about membrane proteins. We propose to examine by solid-state NMR, the structure of bacterially expressed 15N labeled receptor fragments which contain transmembrane domains and the critical G protein activating structures. The effect of constitutively activating mutations on the mobility and orientation of both the transmembrane and cytoplasmic structures will be determined to begin to establish the molecular basis for G protein activation.