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XB-ART-9779
J Cell Biol December 25, 2000; 151 (7): 1525-36.
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The role of Xgrip210 in gamma-tubulin ring complex assembly and centrosome recruitment.

Zhang L , Keating TJ , Wilde A , Borisy GG , Zheng Y .


Abstract
The gamma-tubulin ring complex (gammaTuRC), purified from the cytoplasm of vertebrate and invertebrate cells, is a microtubule nucleator in vitro. Structural studies have shown that gammaTuRC is a structure shaped like a lock-washer and topped with a cap. Microtubules are thought to nucleate from the uncapped side of the gammaTuRC. Consequently, the cap structure of the gammaTuRC is distal to the base of the microtubules, giving the end of the microtubule the shape of a pointed cap. Here, we report the cloning and characterization of a new subunit of Xenopus gammaTuRC, Xgrip210. We show that Xgrip210 is a conserved centrosomal protein that is essential for the formation of gammaTuRC. Using immunogold labeling, we found that Xgrip210 is localized to the ends of microtubules nucleated by the gammaTuRC and that its localization is more distal, toward the tip of the gammaTuRC-cap structure, than that of gamma-tubulin. Immunodepletion of Xgrip210 blocks not only the assembly of the gammaTuRC, but also the recruitment of gamma-tubulin and its interacting protein, Xgrip109, to the centrosome. These results suggest that Xgrip210 is a component of the gammaTuRC cap structure that is required for the assembly of the gammaTuRC.

PubMed ID: 11134080
PMC ID: PMC2150686
Article link: J Cell Biol
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: grip1 tub tubg1 tubgcp3 tubgcp6


Article Images: [+] show captions
References [+] :
Desai, Microtubule polymerization dynamics. 1998, Pubmed