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Your search keyword '"Oka, Toshihiko"' showing total 15 results
Start Over Author "Oka, Toshihiko" Publisher american chemical society (acs)
15 results on '"Oka, Toshihiko"'

3. Conformational differences among metarhodopsin I, metarhodopsin II, and opsin probed by wide-angle X-ray scattering

Author

80263200, Imamoto, Yasushi, Kojima, Keiichi, Oka, Toshihiko, Maeda, Ryo, Shichida, Yoshinori, 80263200, Imamoto, Yasushi, Kojima, Keiichi, Oka, Toshihiko, Maeda, Ryo, and Shichida, Yoshinori

Abstract

Among the photoproducts of vertebrate rhodopsin, only metarhodopsin II (Meta-II) preferentially adopts the active structure in which transmembrane helices are rearranged. Light-induced helical rearrangement of rhodopsin in membrane-embedded form was directly monitored by wide-angle X-ray scattering (WAXS) using nanodiscs. The change in the WAXS curve for the formation of Meta-II was characterized by a peak at 0.2 Å⁻¹ and a valley at 0.6 Å⁻¹, which were not observed in metarhodopsin I and opsin. However, acid-induced active opsin (Opsin*) showed a 0.2 Å⁻¹ peak, but no 0.6 Å⁻¹ valley. Analyses using the model structures based on the crystal structures of dark state and Meta-II suggest that the outward movement of helix VI occurred in Opsin*. However, the displaced helices III and V in Meta-II resulting from the disruption of cytoplasmic ionic lock were restored in Opsin*, which is likely to destabilize the G-protein-activating structure of opsin.

Published
2019

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