Dynamic localization nuclear import receptor and its interactions with transport factors
Dynamic localization nuclear import receptor and its interactions with transport factors
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DOI：
10.1083/jcb.133.6.1163
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发表时间：
1996-06-01
影响因子：
7.8
通讯作者：
Silver, PA
中科院分区：
文献类型：
--
作者：
Koepp, DM;Wong, DH;Silver, PA
表征核运输所需的可溶性因子之间的相互作用是理解核运输过程的关键。利用rnal-1菌株的合成致死筛选，我们已经确定了Rnalp（核运输所需的GTPase激活蛋白）和酵母importin- β（核定位信号受体的组成部分）之间的遗传相互作用。通过使用融合蛋白，我们证明了Rnalp与importin- β的物理相互作用。importin-beta的突变体在体内表现出核蛋白进口缺陷，并且importin-beta与其他与核孔复合物相关的蛋白质一起定位于核膜。此外，我们提供的证据表明，在GTPase Ran可能处于gdp结合状态的细胞中，importin- α而不是importin- β会错定位到细胞核中。我们提出了一种核转运模型，其中Ran介导的GTP水解是将importin- α和携带核定位信号的底物输入细胞核所必需的，而GTP在Ran上的交换是mRNA和importin- α从细胞核输出所必需的。
Characterization of the interactions between soluble factors required for nuclear transport is key to understanding the process of nuclear trafficking. Using a synthetic lethal screen with the rnal-1 strain, we have identified a genetic interaction between Rnalp, a GTPase activating protein required for nuclear transport, and yeast importin-beta, a component of the nuclear localization signal receptor. By the use of fusion proteins, we demonstrate that Rnalp physically interacts with importin-beta. Mutants in importin-beta exhibit in vivo nuclear protein import defects, and importin-beta localizes to the nuclear envelope along with other proteins associated with the nuclear pore complex. In addition, we present evidence that importin-alpha, but not importin-beta, mislocalizes to the nucleus in cells where the GTPase Ran is likely to be in the GDP-bound state. We suggest a model of nuclear transport in which Ran-mediated hydrolysis of GTP is necessary for the import of importin-alpha and the nuclear localization signal-bearing substrate into the nucleus, while exchange of GDP for GTP on Ran is required for the export of both mRNA and importin-alpha from the nucleus.