Leguy R, Melki R, Pantaloni D, Carlier M F
Dynamique du Cytosquelette, Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, 91198 Gif-sur-Yvette, France.
J Biol Chem. 2000 Jul 21;275(29):21975-80. doi: 10.1074/jbc.M000688200.
gamma-Tubulin is required for nucleation and polarized organization of microtubules in vivo. The mechanism of microtubule nucleation by gamma-tubulin and the role of associated proteins is not understood. Here we show that in vitro translated monomeric gamma-tubulin nucleates microtubules by lowering the size of the nucleus from seven to three tubulin subunits. In capping the minus end with high affinity (10(10) m(-1)) and a binding stoichiometry of one molecule of gamma-tubulin/microtubule, gamma-tubulin establishes the critical concentration of the plus end in the medium and prevents minus end growth. gamma-Tubulin interacts strongly with beta-tubulin. A structural model accounts for these results.
γ-微管蛋白是体内微管成核和极化组织所必需的。γ-微管蛋白介导微管成核的机制以及相关蛋白的作用尚不清楚。在此我们表明，体外翻译的单体γ-微管蛋白通过将核的大小从七个微管蛋白亚基降低到三个，从而实现微管的成核。γ-微管蛋白以高亲和力（10¹⁰ m⁻¹）封端负端，且结合化学计量为一分子γ-微管蛋白/微管，它确定了培养基中正端的临界浓度并阻止负端生长。γ-微管蛋白与β-微管蛋白强烈相互作用。一个结构模型解释了这些结果。
