| Project/Area Number |
11670099
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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 | 一般 |
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| Research Field |
General pharmacology
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| Research Institution | Saitama Medical University |
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Principal Investigator |
ENDO Makoto Saitama Medical School, Faculty of Medicine, Professor, 医学部, 教授 (50009990)
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| Co-Investigator(Kenkyū-buntansha) |
IKEMOTO Takaaki Saitama Medical School, Faculty of Medicine, Reseach Associate, 医学部, 助手 (30275854)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2000: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1999: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Keywords | ryanodine receptor / Ca-induced Ca release (CICR) / clofibric acid / dantrolene / photoaffinity labeling / reticulon 2C / calcium ion / excitation-contraction coupling / 筋小胞体 / リアノジン受容体 / Ca induced Ca release / ダントロレン / clofibric acid / アデニン化合物 / プロカイン / Ca放出 |
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| Research Abstract |
Ryanodine receptor(RyR)/Calcium release channel of the sarcoplasmic reticulum of skeletal muscle opens in two different modes, physiological mode and calcium-induced calcium release (CICR) mode. In order to find out the molecular basis of the two kinds of mode, we searched an agent that specifically affects one of the two modes, (1) We found that clofibric acid opens RyR in the mode similar to the physiological one. This is the first example of such an agent. (2) Since we previously found that dantrolene can discriminate the two kinds of mode under a certain temperature condition, we examined various derivatives of dantrolene and found that GIF-0082 specifically inhibits without interacting CICR mechanism. (3) Since GIF-0082 contains iodine in it and has a radical with which photoaffinity labeling can be carried out, we prepared radioactive GIF-0082 with <125>^I and tried to find out GIF-0082 binding protein(s). The redioligand did not bind RyR molecules, but it bound 23 kDa protein in the fragmented sarcoplasmic reticulum. We isolated and purified this protein and determined its amino acid sequence that was found to be similar to sequence of reticulon 2C of mouse and human. (4) There is also GIF-0082 binding protein in the soluble fraction of skeletal muscle cells, a 45 kDa protein. The binding of [<125>^I]-GIF-0082 to 23 kDa protein was inhibited by dantrolene but only at its high concentration (20-5O /μM), but that to 45 kDa protein was effectively inhibited by a low concentration of dantrolene. The 4S kDa protein, although soluble, can bind RyR under an appropriate condition. These results suggest that the above-mentioned proteins, especially the 45 kDa protein, might play an important role in the physiological calcium release process. We are currently investigating in this direction
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