Importin β is a mitotic target of the small GTPase ran in spindle assembly
Importin β is a mitotic target of the small GTPase ran in spindle assembly
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DOI：
10.1016/s0092-8674(01)00194-5
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发表时间：
2001-01-12
期刊：
影响因子：
64.5
通讯作者：
Weis, K
中科院分区：
文献类型：
--
作者：
Nachury, MV;Maresca, TJ;Weis, K
最近已显示GTdR Ran刺激有丝分裂提取物中的微管聚合，但其作用方式尚不清楚。在这里，我们表明，有丝分裂的作用，RAN主要是介导的核转运因子importin β。Importin β在体外和体内抑制纺锤体形成，并隔离由多个独立因子组成的aster促进活性（阿帕）。阿帕的一个组成部分是微管相关蛋白NuMA。NuMA和其他阿帕组分通过RanGTP从输入蛋白β中排出，并在不存在中心体、染色质或Ran的情况下诱导纺锤体样结构。我们建议，RanGTP的功能在有丝分裂的间期局部释放货物的运输因子。在有丝分裂中，它通过组织染色体附近的微管来促进纺锤体组装。
The GTPase Ran has recently been shown to stimulate microtubule polymerization in mitotic extracts, but its mode of action is not understood. Here we show that the mitotic role of Ran is largely mediated by the nuclear transport factor importin beta. Importin beta inhibits spindle formation in vitro and in vivo and sequesters an aster promoting activity (APA) that consists of multiple, independent factors. One component of APA is the microtubule-associated protein NuMA. NuMA and other APA components are discharged from importin beta by RanGTP and induce spindle-like structures in the absence of centrosomes, chromatin, or Ran. We propose that RanGTP functions in mitosis as in interphase by locally releasing cargoes from transport factors. In mitosis, this promotes spindle assembly by organizing microtubules in the vicinity of chromosomes.