Raff J W, Kellogg D R, Alberts B M
Department of Biochemistry and Biophysics, University of California, San Francisco 94143-0448.
J Cell Biol. 1993 May;121(4):823-35. doi: 10.1083/jcb.121.4.823.
gamma-tubulin is a minor tubulin that is localized to the microtubule organizing center of many fungi and higher eucaryotic cells (Oakley, B. R., C. E. Oakley, Y. Yoon, and M. C. Jung. 1990. Cell. 61: 1289-1301; Stearns, T., L. Evans, and M. Kirschner. 1991. Cell. 65:825-836; Zheng, Y., M. K. Jung, and B. R. Oakley. 1991. Cell. 65:817-823). Here we show that gamma-tubulin is a component of a previously isolated complex of Drosophila proteins that contains at least two centrosomal microtubule-associated proteins called DMAP190 and DMAP60. Like DMAP190 and DMAP60, the gamma-tubulin in extracts of early Drosophila embryos binds to microtubules, although this binding may be indirect. Unlike DMAP190 and DMAP60, however, only 10-50% of the gamma-tubulin in the extract is able to bind to microtubules. We show that gamma-tubulin binds to a microtubule column as part of a complex, and a substantial fraction of this gamma-tubulin is tightly associated with DMAP60. As neither alpha- nor beta-tubulin bind to microtubule columns, the gamma-tubulin cannot be binding to such columns in the form of an alpha:gamma or beta:gamma heterodimer. These observations suggest that gamma-tubulin, DMAP60, and DMAP190 are components of a centrosomal complex that can interact with microtubules.
γ-微管蛋白是一种次要的微管蛋白，定位于许多真菌和高等真核细胞的微管组织中心（奥克利，B.R.，C.E.奥克利，Y.尹，和M.C.荣格。1990年。《细胞》。61: 1289 - 1301；斯特恩斯，T.，L.埃文斯，和M.基尔希纳。1991年。《细胞》。65: 825 - 836；郑，Y.，M.K.荣格，和B.R.奥克利。1991年。《细胞》。65: 817 - 823）。在此我们表明，γ-微管蛋白是先前分离出的果蝇蛋白质复合物的一个组分，该复合物包含至少两种称为DMAP190和DMAP60的中心体微管相关蛋白。与DMAP190和DMAP60一样，早期果蝇胚胎提取物中的γ-微管蛋白能与微管结合，尽管这种结合可能是间接的。然而，与DMAP190和DMAP60不同的是，提取物中只有10% - 50%的γ-微管蛋白能够与微管结合。我们表明，γ-微管蛋白作为复合物的一部分与微管柱结合，并且该γ-微管蛋白的很大一部分与DMAP60紧密相关。由于α-微管蛋白和β-微管蛋白都不与微管柱结合，所以γ-微管蛋白不可能以α:γ或β:γ异二聚体的形式与这样的柱结合。这些观察结果表明，γ-微管蛋白、DMAP60和DMAP190是一个能够与微管相互作用的中心体复合物的组分。
