1999 Fiscal Year Final Research Report Summary
Localization and molecular function of G protein andγ-tubulin in the mitotic apparatus
| Project/Area Number |
10680677
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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 |
Cell biology
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| Research Institution | Japan Women's University, Faculty of Science |
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Principal Investigator |
SAKAI Hikoichi Japan Women's University, Faculty of Science, Chemical and Biological Sciences, Professor, 理学部, 教授 (80011477)
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| Co-Investigator(Kenkyū-buntansha) |
OSUMI Masako Japan Women's University, Faculty of Science, Chemical and Biological Sciences, Professor, 理学部, 教授 (60060646)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Mitotic apparatus / G protein / γ-tubulin / Centrosome / Microtubule |
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| Research Abstract |
The centrosomes of sea urchin egg function as an organizing center of the mitotic apparatus (MA), containing a G protein of MW 51,000 (p51) which serves as a component of the nucleus in microtubule assembly. This protein component is contained in the microtubule-organizing granules (MTOG). On the the hand, it has been shown that γ-tubulin and Ran- GTP binding protein are localized to the centrosome, playing a role in microtubule nucleation. Then, MTOG fraction was prepared from both unfertilized and fertilize sea urchin eggs and localization or γ-tubulin was analized by Western blotting. However, we failed to detect γ-tubulin in the MTOG fraction. We, of course, confirmed a strong signal of p51 from the MTOG fraction. The MTOG fraction was adsorbed on the surface of Latex beads, forming astral-shaped microtubule assembly. The protein components bound to the Latex beads did not contain γ-tubulin. The aster formation initiated from the Latex beads was strongly inhibited by anti-p51 antibodies but slightly by anti-γ-tubulin aantibodies. Therefore, there is a possiblility that γ-tubulin does not work in sea urchin egg, although the possibility that cells possess redundant machinery for initiation of microtubule in MA formation would not be excluded.
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