A novel photointermediate of octopus rhodopsin activates its G‐protein

FEBS Letters

Tominaga, Kayo¹  Nakagawa, Masashi¹  Kikkawa, Satoshi¹  Tsugi, Naoko¹  Tsuda, Motoyuki¹ 

[1] Department of Life Science, Himeji Institute of Technology, Harima Science Garden City, Akoh-gun, Hyogo 678-1297, Japan

关键词: Octopus rhodopsin;    G-protein;    Metarhodopsin;    Photointermediate;    Laser photolysis;    FTIR;    Fourier-transform infrared spectroscopy;    G-protein;    guanine nucleotide-binding protein;    PLC;    phospholipase C;    APMSF;    4-(amidinophenyl)methanesulfonyl fluoride;    DTT;    dithiothreitol;    GTPγS;    guanosine 5′-(3-O-thio)triphosphate;    MES;    2-(N-morpholino) ethane sulfonic acid;   

DOI  :  10.1016/S0014-5793(98)01138-7

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The photointermediate of octopus rhodopsin responsible for G-protein activation was examined by a GTPγS-binding assay in a reconstituted system with purified rhodopsin and photoreceptor G-protein. When octopus rhodopsin alone was incubated in the dark after illumination, its ability to stimulate GTPγS-binding by the G-protein decreased in a time-dependent manner. We associate this decay with the decay of a novel photointermediate, transient acid metarhodopsin, which lies between mesorhodopsin and acid metarhodopsin. Spectroscopic evidence for its existence was suggested by its effects on the turbidity of the vesicles. These results suggest that the transient acid metarhodopsin, not the stable final photoproduct, acid metarhodopsin, activates a G-protein in octopus photoreceptors.

【 授权许可】

Unknown