期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2001
卷号：98
期号：9
页码：4888-4892
DOI：10.1073/pnas.051633098
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：19F nuclear Overhauser effects (NOEs) between fluorine labels on the cytoplasmic domain of rhodopsin solubilized in detergent micelles are reported. Previously, high-resolution solution 19F NMR spectra of fluorine-labeled rhodopsin in detergent micelles were described, demonstrating the applicability of this technique to studies of tertiary structure in the cytoplasmic domain. To quantitate tertiary contacts we have applied a transient one-dimensional difference NOE solution 19F NMR experiment to this system, permitting assessment of proximities between fluorine labels specifically incorporated into different regions of the cytoplasmic face. Three dicysteine substitution mutants (Cys-140-Cys-316, Cys-65-Cys-316, and Cys-139-Cys-251) were labeled by attachment of the trifluoroethylthio group through a disulfide linkage. Each mutant rhodopsin was prepared (8-10 mg) in dodecylmaltoside and analyzed at 20{degrees}C by solution 19F NMR. Distinct chemical shifts were observed for all of the rhodopsin 19F labels in the dark. An up-field shift of the Cys-316 resonance in the Cys-65-Cys-316 mutant suggests a close proximity between the two residues. When analyzed for 19F-19F NOEs, a moderate negative enhancement was observed for the Cys-65-Cys-316 pair and a strong negative enhancement was observed for the Cys-139-Cys-251 pair, indicating proximity between these sites. No NOE enhancement was observed for the Cys-140-Cys-316 pair. These NOE effects demonstrate a solution 19F NMR method for analysis of tertiary contacts in high molecular weight proteins, including membrane proteins.
关键词：G protein-coupled receptors ; signal transduction ; site-directed 19F labeling ; NMR structure contacts ; membrane protein
