|Budget Amount *help
¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 1993 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1992 : ¥1,300,000 (Direct Cost : ¥1,300,000)
The aim of this project research was to elucidate an molecular mechanism of signal transduction and that of modulation of the system.The system for photasignal transduction is one of the most elucidated G-protein coupled signal transduction system, which is composed of photoreceptor rhodopsin, signal transducer G-protein, and several modulator of the system such as rhodopsin kinase, arrestin, and S-modulin.We first planned to make a model system with rhodopsin from invertebrate and G-protein from vertebrate, because an invertebrate rhodopsin in photoreversible and a reconstituted model system with an invertebrate rhodopsin can be used repeatedly.We used an octopus rhodopsin for making the model system.On the course of the study we found that octopus rhodopsin couples with a different class of G-protein from transducin, a G-protein participating vertebrate photosignal transduction system.Thus the study to elucidate and to characterize the octopus photosignal transduction system was main
ly progressed.The achievements with this project were listed below.
1) A new long-lived photointermediate was found in the photoreaction process of octopus rhodopsin.This intermediate is a candidate couples with G-protein on Octopus photosignal transduction system.2) The molecular structure of a N-linked sugar chain of octopus rhodopsin was elucidated and found to be a new one.3) We found four different classed of alpha subunit of G-protein were expressed in octopus eye.An alpha subunit of G-protein in the same class as transducin was not found.4) Northern blot analysis of alpha subunits of octopus G-protein elucidates that Gq class was predominately expressed in the eye of octopus.5) We found, although, only one class of beta subunit of G-protein from octopus eye and optic lobe.6) We succeeded to express opsin protein with vaccuro virus and Sf9 insect cultured cell.7) We succeeded to bleach and to reconstitute octopus rhodopsin.This technique makes it possible to supply an analog pigment of rhodopsin.8) Using a vesicle reconstituted with octopus rhodopsin, we found that two classes of G-protein, Gqp and Gip, coupled with photo-activated octopus rhodopsin. Less