Molecular properties of rhodopsin and rod function

Hiroo Imai, Vladimir Kefalov, Keisuke Sakurai, Osamu Chisaka, Yoshiki Ueda, Akishi Onishi, Takefumi Morizumi, Yingbin Fu, Kazuhisa Ichikawa, Kei Nakatani, Yoshihito Honda, Jeannie Chen, King-Wai Yau, Yoshinori Shichida

Research output: Contribution to journalArticle

Abstract

Signal transduction in rod cells begins with photon absorption by rhodopsin and leads to the generation of an electrical response. The response profile is determined by the molecular properties of the phototransduction components. To examine how the molecular properties of rhodopsin correlate with the rod-response profile, we have generated a knock-in mouse with rhodopsin replaced by its E122Q mutant, which exhibits properties different from those of wild-type (WT) rhodopsin. Knock-in mouse rods with E122Q rhodopsin exhibited a photosensitivity about 70% of WT. Correspondingly, their single-photon response had an amplitude about 80% of WT, and a rate of decline from peak about 1.3 times of WT. The overall 30% lower photosensitivity of mutant rods can be explained by a lower pigment photosensitivity (0.9) and the smaller single-photon response (0.8). The slower decline of the response, however, did not correlate with the 10-fold shorter lifetime of the meta-II state of E122Q rhodopsin. This shorter lifetime became evident in the recovery phase of rod cells only when arrestin was absent. Simulation analysis of the photoresponse profile indicated that the slower decline and the smaller amplitude of the single-photon response can both be explained by the shift in the meta-I/meta-II equilibrium of E122Q rhodopsin toward meta-I. The difference in meta-III lifetime between WT and E122Q mutant became obvious in the recovery phase of the dark current after moderate photobleaching of rod cells. Thus, the present study clearly reveals how the molecular properties of rhodopsin affect the amplitude, shape, and kinetics of the rod response.

Original languageEnglish (US)
Pages (from-to)6677-6684
Number of pages8
JournalJournal of Biological Chemistry
Volume282
Issue number9
DOIs
StatePublished - Mar 2 2007

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Rhodopsin
Photons
Photosensitivity
Light Signal Transduction
Photobleaching
Arrestin
Recovery
Signal transduction
Dark currents
Pigments
Signal Transduction
Kinetics

ASJC Scopus subject areas

  • Biochemistry

Cite this

Imai, H., Kefalov, V., Sakurai, K., Chisaka, O., Ueda, Y., Onishi, A., ... Shichida, Y. (2007). Molecular properties of rhodopsin and rod function. Journal of Biological Chemistry, 282(9), 6677-6684. https://doi.org/10.1074/jbc.M610086200

Molecular properties of rhodopsin and rod function. / Imai, Hiroo; Kefalov, Vladimir; Sakurai, Keisuke; Chisaka, Osamu; Ueda, Yoshiki; Onishi, Akishi; Morizumi, Takefumi; Fu, Yingbin; Ichikawa, Kazuhisa; Nakatani, Kei; Honda, Yoshihito; Chen, Jeannie; Yau, King-Wai; Shichida, Yoshinori.

In: Journal of Biological Chemistry, Vol. 282, No. 9, 02.03.2007, p. 6677-6684.

Research output: Contribution to journalArticle

Imai, H, Kefalov, V, Sakurai, K, Chisaka, O, Ueda, Y, Onishi, A, Morizumi, T, Fu, Y, Ichikawa, K, Nakatani, K, Honda, Y, Chen, J, Yau, K-W & Shichida, Y 2007, 'Molecular properties of rhodopsin and rod function', Journal of Biological Chemistry, vol. 282, no. 9, pp. 6677-6684. https://doi.org/10.1074/jbc.M610086200
Imai H, Kefalov V, Sakurai K, Chisaka O, Ueda Y, Onishi A et al. Molecular properties of rhodopsin and rod function. Journal of Biological Chemistry. 2007 Mar 2;282(9):6677-6684. https://doi.org/10.1074/jbc.M610086200
Imai, Hiroo ; Kefalov, Vladimir ; Sakurai, Keisuke ; Chisaka, Osamu ; Ueda, Yoshiki ; Onishi, Akishi ; Morizumi, Takefumi ; Fu, Yingbin ; Ichikawa, Kazuhisa ; Nakatani, Kei ; Honda, Yoshihito ; Chen, Jeannie ; Yau, King-Wai ; Shichida, Yoshinori. / Molecular properties of rhodopsin and rod function. In: Journal of Biological Chemistry. 2007 ; Vol. 282, No. 9. pp. 6677-6684.
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AU - Morizumi, Takefumi

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