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Title: Single-molecule observation of the ligand-induced population shift of rhodopsin, a g-protein-coupled receptor.
Authors: Maeda, Ryo
Hiroshima, Michio
Yamashita, Takahiro  kyouindb  KAKEN_id
Wada, Akimori
Nishimura, Shoko
Sako, Yasushi
Shichida, Yoshinori  kyouindb  KAKEN_id
Imamoto, Yasushi  kyouindb  KAKEN_id  orcid (unconfirmed)
Author's alias: 今元, 泰
Issue Date: 18-Feb-2014
Publisher: Elsevier Inc.
Journal title: Biophysical journal
Volume: 106
Issue: 4
Start page: 915
End page: 924
Abstract: Rhodopsin is a G-protein-coupled receptor, in which retinal chromophore acts as inverse-agonist or agonist depending on its configuration and protonation state. Photostimulation of rhodopsin results in a pH-dependent equilibrium between the active state (Meta-II) and its inactive precursor (Meta-I). Here, we monitored conformational changes of rhodopsin using a fluorescent probe Alexa594 at the cytoplasmic surface, which shows fluorescence increase upon the generation of active state, by single-molecule measurements. The fluorescence intensity of a single photoactivated rhodopsin molecule alternated between two states. Interestingly, such a fluorescence alternation was also observed for ligand-free rhodopsin (opsin), but not for dark-state rhodopsin. In addition, the pH-dependences of Meta-I/Meta-II equilibrium estimated by fluorescence measurements deviated notably from estimates based on absorption spectra, indicating that both Meta-I and Meta-II are mixtures of two conformers. Our observations indicate that rhodopsin molecules intrinsically adopt both active and inactive conformations, and the ligand retinal shifts the conformational equilibrium. These findings provide dynamical insights into the activation mechanisms of G-protein-coupled receptors.
Rights: © 2014 Biophysical Society. Published by Elsevier Inc.
This is not the published version. Please cite only the published version. この論文は出版社版でありません。引用の際には出版社版をご確認ご利用ください。
DOI(Published Version): 10.1016/j.bpj.2014.01.020
PubMed ID: 24559994
Appears in Collections:Journal Articles

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