1996 Fiscal Year Final Research Report Summary
Molecular mechanism of phototransduction in rhabdomeric photoreceptors.
| Project/Area Number |
07839018
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 時限 |
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| Research Field |
光生物学
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| Research Institution | Hyogo College of Medicine |
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Principal Investigator |
SUZUKI Tatsuo Hyogo College of Medicine, Faculty of Medicine, Assistant Professor, 医学部, 講師 (90068544)
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| Project Period (FY) |
1995 – 1996
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| Keywords | Cell Signaling / Photoreception / Photoreceptor Cell / Rhodopsin / GTP-binding Protein / Phospholipase C |
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| Research Abstract |
The object of this research project was to prove the rhodopsin/G-protein/phospholipase C cascade in rhabdomeric photoreceptors. The following results were obtained. 1. The experiments of immunoprecipitation demonstrated that photo-activated rhodopsin formed complex with alpha subunit of Gq and that the complex dissociated in the presence of GTP.2. Reconstitution experiments demonstrated that PLC was acitvated by GTP-bound Gqalpha and not by Gbetagamma.3. GTPgammaS-binding experiments demonstrated that GDP-GTP exchange reaction was very slow in soluble Gqalpha in contrast to extremely rapid one in membrane Gqalpha. The potency of PLC-activation of soluble Gqalpha is a half of that of membrane Gqalpha. 4. The reversible translocation of Gqalpha between membrane and cytosol in response to light was shown in crayfish retina by biochemical and immunocytochemical experiments. The transformation of membrane Gqalpha to soluble Gqalpha was suggested to be due to depalmitoylation of Gqalpha from the results of hydroxyl amine-treatment.
These results showed that rhodopsin/Gq-class G-protein/phospholipase C cascade is the main pathway of phototransduction and suggested that the translocation of Gqalpha is one of the molecular mechanisms of light-adaptation of rhabdomeric photoreceptor cells to regulate photosensitivity.
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