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Localization and molecular function of G protein andγ-tubulin in the mitotic apparatus

G 蛋白和 γ-微管蛋白在有丝分裂器中的定位和分子功能

基本信息

批准号：
10680677
负责人：
SAKAI Hikoichi
金额：
$ 2.11万
依托单位：
Japan Women's University, Faculty of Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10680677/
关键词：
Mitotic apparatus G protein γ-tubulin Centrosome Microtubule γ-チューブリンチューブリン星状体

项目摘要

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.

海胆卵的中心体作为有丝分裂器（MA）的组织中心发挥作用，含有MW 51，000（p51）的G蛋白，其作为微管组装中的核组分。这种蛋白质成分包含在微管组织颗粒（MTOG）中。另一方面，已经表明γ-微管蛋白和Ran- GTP结合蛋白定位于中心体，在微管成核中起作用。然后，从未受精和受精的海胆卵中制备MTOG组分，并通过Western印迹分析γ-微管蛋白的定位。然而，我们未能在MTOG组分中检测到γ-微管蛋白。当然，我们证实了来自MTOG组分的p51的强信号。MTOG组分吸附在乳胶珠表面，形成星形微管组装体。与Latex微珠结合的蛋白质组分不含γ-微管蛋白。抗p51抗体强烈抑制乳胶珠引发的星形细胞形成，而抗γ-微管蛋白抗体则轻微抑制。因此，γ-微管蛋白在海胆卵中不起作用的可能性是存在的，尽管不排除细胞具有启动MA形成中微管的冗余机制的可能性。