Klein-Seetharaman Judith, Yanamala Naveena V K, Javeed Fathima, Reeves Philip J, Getmanova Elena V, Loewen Michele C, Schwalbe Harald, Khorana H Gobind
Department of Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.
Proc Natl Acad Sci U S A. 2004 Mar 9;101(10):3409-13. doi: 10.1073/pnas.0308713101. Epub 2004 Feb 27.
G protein-coupled receptors are cell-surface seven-helical membrane proteins that undergo conformational changes on activation. The mammalian photoreceptor, rhodopsin, is the best-studied member of this superfamily. Here, we provide the first evidence that activation in rhodopsin may involve differential dynamic properties of side-chain versus backbone atoms. High-resolution NMR studies of alpha-(15)N-labeled receptor revealed large backbone motions in the inactive dark state. In contrast, indole side-chain (15)N groups of tryptophans showed well resolved, equally intense NMR signals, suggesting restriction to a single specific conformation.
G蛋白偶联受体是细胞表面的七螺旋膜蛋白,激活时会发生构象变化。哺乳动物光感受器视紫红质是这个超家族中研究得最透彻的成员。在这里,我们提供了首个证据,表明视紫红质的激活可能涉及侧链原子与主链原子不同的动态特性。对α-(15)N标记受体的高分辨率核磁共振研究显示,在无活性的暗态下主链有大幅运动。相比之下,色氨酸的吲哚侧链(15)N基团显示出分辨率良好、强度相同的核磁共振信号,表明其被限制在单一特定构象中。