| Project/Area Number |
18310088
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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 |
Nanomaterials/Nanobioscience
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| Research Institution | Kobe University |
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Principal Investigator |
HAYASHI Fumio Kobe University, Graduate Sch. Sci., Biology, Professor (80093524)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥14,780,000 (Direct Cost: ¥13,400,000、Indirect Cost: ¥1,380,000)
Fiscal Year 2007: ¥5,980,000 (Direct Cost: ¥4,600,000、Indirect Cost: ¥1,380,000)
Fiscal Year 2006: ¥8,800,000 (Direct Cost: ¥8,800,000)
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| Keywords | single molecule observation / transducin / G protein / rhodopsin / phototransduction / hotorecentor / trafficking / disk membrane / G蛋白質 / トラフィックング |
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| Research Abstract |
The main purpose of this research is to clarify the operating mechanism of G protein transducin in vertebrate photoreceptor disk membranes by single molecular imaging technique. The second purpose is to examine the molecular mechanism of G protein trafficking between inner and outer segment of rod photoreceptor during light- or dark adaptation. As the first task to clear, PI challenged to label transducin with near-infrared fluorescent compound (Hilyte 750), and succeeded. The labeled transducin retained its normal activity in binding light-bleached rhodopsin, nucleotide exchange activity, and PDE6 activation. By using this fluorescent-labeled transducin, Pl succeeded to observe single molecular motion of transducin in the dark state by using 750 nm laser beam for excitation of the label. Transducin showed much faser diffusion than rhodopsin in dark-adapted disk membrane. Upon exposure to visible light, transducin forms complex with light-bleached rhodopsin, and the complex showed slow
… More
er diffusion than rhodopsin. The diffusion rate of the complex was dependent on cholesterol-content of the disk membrane, i.e. the cholesterol-depletion by cholesterol-binding compound methyl-beta-cyclodextrin speeded up the diffusion of transducin-rhodopsin complex, suggesting that the activation of transducin occurs at the peripheries of cholesterol-dependent microdomains in the disk membrane. Although the mechanism of the microdomain formation has not been elucidated, these result gave us a deeper and new insight I into the G protein signaling mechanism of vertebrate phototransduction system. As for the trafficking of transducin between inner and outer segment of rod photoreceptor, Pl has not been able to introduce fluorescent-labeled transducin into rod outer segment. However, Pl's finding that GTP-form transducin shows propensity to form aggregation at the peripheral spots seemingly tubulin fibers at the mouth of incisures of the disk membrane suggested the importance of the interaction between transducin with tubulin in the trafficking. Papers about the single molecular behavior of transducin and its complex with rhodopsin are now in preparation. Less
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