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XB-ART-13477
J Cell Biol 1999 Feb 22;1444:721-33.
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Characterization of two related Drosophila gamma-tubulin complexes that differ in their ability to nucleate microtubules.

Oegema K , Wiese C , Martin OC , Milligan RA , Iwamatsu A , Mitchison TJ , Zheng Y .


Abstract
gamma-tubulin exists in two related complexes in Drosophila embryo extracts (Moritz, M., Y. Zheng, B.M. Alberts, and K. Oegema. 1998. J. Cell Biol. 142:1- 12). Here, we report the purification and characterization of both complexes that we name gamma-tubulin small complex (gammaTuSC; approximately 280,000 D) and Drosophila gammaTuRC ( approximately 2,200,000 D). In addition to gamma-tubulin, the gammaTuSC contains Dgrip84 and Dgrip91, two proteins homologous to the Spc97/98p protein family. The gammaTuSC is a structural subunit of the gammaTuRC, a larger complex containing about six additional polypeptides. Like the gammaTuRC isolated from Xenopus egg extracts (Zheng, Y., M.L. Wong, B. Alberts, and T. Mitchison. 1995. Nature. 378:578-583), the Drosophila gammaTuRC can nucleate microtubules in vitro and has an open ring structure with a diameter of 25 nm. Cryo-electron microscopy reveals a modular structure with approximately 13 radially arranged structural repeats. The gammaTuSC also nucleates microtubules, but much less efficiently than the gammaTuRC, suggesting that assembly into a larger complex enhances nucleating activity. Analysis of the nucleotide content of the gammaTuSC reveals that gamma-tubulin binds preferentially to GDP over GTP, rendering gamma-tubulin an unusual member of the tubulin superfamily.

PubMed ID: 10037793
PMC ID: PMC2132928

Grant support: [+]

Species referenced: Xenopus
Genes referenced: cat.1 tbx2 tubg1


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References [+] :
Burns, Analysis of the gamma-tubulin sequences: implications for the functional properties of gamma-tubulin. 1995, Pubmed