期刊
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
卷 53, 期 8, 页码 2078-2084出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/anie.201309581
关键词
bovine rhodopsin; G-protein coupled receptors; membrane protein dynamics; NMR spectroscopy; photocycles
资金
- DFG [SFB807]
- NSF [1144281]
- Division of Computing and Communication Foundations
- Direct For Computer & Info Scie & Enginr [1144281] Funding Source: National Science Foundation
The mammalian visual dim-light photoreceptor rhodopsin is considered a prototype Gprotein-coupled receptor. Here, we characterize the kinetics of its light-activation process. Milligram quantities of ,epsilon-N-15-labeled tryptophan rhodopsin were produced in stably transfected HEK293 cells. Assignment of the chemical shifts of the indole signals was achieved by generating the single-point-tryptophan to phenylalanine mutants, and the kinetics of each of the five tryptophan residues were recorded. We find kinetic partitioning in rhodopsin decay, including three half-lives, that reveal two parallel processes subsequent to rhodopsin activation that are related to the photocycle. The metaII and metaIII states emerge in parallel with a relative ratio of about 3:1. Transient formation of the metaIII state was confirmed by flash photolysis experiments. From analysis of the site-resolved kinetic data we propose the involvement of the E-2-loop in the formation of the metaIII state.
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