Nat Cell Biol. 2014 Aug;16(8):770-8. doi: 10.1038/ncb2996. Epub 2014 Jun 29.
During mitotic spindle assembly, γ-tubulin ring complexes (γTuRCs) nucleate microtubules at centrosomes, around chromosomes, and, by interaction with augmin, from pre-existing microtubules. How different populations of microtubules are organized to form a bipolar spindle is poorly understood, in part because we lack information on the dynamics of microtubule minus ends. Here we show that γTuRC is associated with minus ends of non-centrosomal spindle microtubules. Recruitment of γTuRC to spindles occurs preferentially at pole-distal regions, requires nucleation and/or interaction with minus ends, and is followed by sorting of minus-end-bound γTuRC towards the poles. Poleward movement of γTuRC exceeds k-fibre flux, involves the motors dynein, HSET (also known as KIFC1; a kinesin-14 family member) and Eg5 (also known as KIF11; a kinesin-5 family member), and slows down in pole-proximal regions, resulting in the accumulation of minus ends. Thus, in addition to nucleation, γTuRC actively contributes to spindle architecture by organizing microtubule minus ends.
在有丝分裂纺锤体组装过程中，γ-微管蛋白环复合物（γTuRC）在中心体、染色体周围以及通过与增敏因子复合物的相互作用，从预先存在的微管上起始微管的形成。不同群体的微管如何组织形成双极纺锤体尚不清楚，部分原因是我们缺乏关于微管负端动力学的信息。在这里，我们表明 γTuRC 与非中心体纺锤体微管的负端相关联。γTuRC 向纺锤体的募集优先发生在极远端区域，需要起始和/或与负端相互作用，随后将结合负端的 γTuRC 分拣到极部。γTuRC 向极部的运动超过 k-纤维流，涉及动力蛋白 dynein、HSET（也称为 KIFC1；一种驱动蛋白-14 家族成员）和 Eg5（也称为 KIF11；一种驱动蛋白-5 家族成员），并在极近端区域减速，导致负端积累。因此，除了起始作用外，γTuRC 通过组织微管负端积极参与纺锤体结构的形成。
