1996 Fiscal Year Final Research Report Summary
Molecular Mechanism of Adaptation of Visual Cells
| Project/Area Number |
07454227
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
動物生理・代謝
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| Research Institution | Osaka University |
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Principal Investigator |
TOKUNAGA Fumio Osaka University, Graduate School of Science, Department of Earth and Space, Professor, 大学院・理学研究科, 教授 (80025452)
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| Co-Investigator(Kenkyū-buntansha) |
HISATOMI Osamu Osaka University, Graduate School of Science, Department of Earth and Space, Res, 大学院・理学研究科, 助手 (60231544)
KATAOKA Mikio Osaka University, Graduate School of Science, Department of Earth and Space, Ass, 大学院・理学研究科, 助教授 (30150254)
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| Project Period (FY) |
1995 – 1996
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| Keywords | Vision / Visual cells / Adaptation / Sensitivity control / Calcium binding protein / Visual Pigments / Intracellular information transduction / Photo-electro-transduction |
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| Research Abstract |
Several kinds of functional proteins, such as G-protein, phosphodiesterase, cGMP dependent cation channel and so on, play important roles in the cascade of visual transduction of visual cells. The transduction pathway is modulated by the light intensity, so called light-dark adaptations. It was reported that the adaptation was controlled by S-modulin in a calcium dependent manner. The following results were clarified by this research.
1) S-modulin homologues of vertebrates were classified into two groups : one is S-modulin group which works in rod cells while another is visinin group which work in cone cells. 2) Tow kinds of proteins of frog, S-modulin and s26 were expressed in E.coli as functional forms. 3) It was confirmed by X-ray small angel scattering that the molecular shape of bovine S-modulin was changed by the calcium concentration and the addition of a myristoyl group. 4) The anti-S-modulin- and anti-s26-antibodies were prepared. The immunohistochemistry with these anti-bodies revealed that S-modulin was expressed in rod cells while s26 was expressed in cone cells. 5) S-modulin had higher affinity to the membrane than s26. In the 500mM salt solution both proteins showed the same affinities. A chimera s26, the c-terminal 23 amino acid residues of which had been substituted by amino acid sequence of S-modulin, showed the same affinity to the membrane as S-modulin, suggesting that the difference in the affinity to the membrane is derived form the differences in the charged residues on the c-terminus. 6) S-modulin was localized in the inner segment of the light adapted rod cells, while S-modulin was distributed in a whole area on the dark adapted rod cells.
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