Transportin: Nuclear transport receptor of a novel nuclear protein import pathway
Transportin: Nuclear transport receptor of a novel nuclear protein import pathway
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DOI：
10.1006/excr.1996.0369
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发表时间：
1996-12-15
影响因子：
3.7
通讯作者：
Dreyfuss, G
中科院分区：
文献类型：
--
作者：
Nakielny, S;Siomi, MC;Dreyfuss, G
许多核蛋白通过“经典”核定位信号（NLS）介导的输入途径输入细胞核。在该途径中，蛋白质中富含碱性残基的序列与称为输入蛋白的异源二聚体复合物相互作用，并且这沿着GT3 Ran介导携带NLS的蛋白质的核输入。异质核核糖核蛋白（hnRNP）A1蛋白含有一个新的核定位序列，称为M9，不含任何集群的碱性残基。最近，我们发现M9通过一种不同于经典NLS途径的新型蛋白质输入途径指导输入细胞核。一个90千道尔顿的蛋白质称为转运蛋白被确定为一种蛋白质，特异性地与野生型M9相互作用，但不运输缺陷型MS突变体。转运蛋白和ATP再生系统被认为是必要的和足够的进口含MS的蛋白质在体外进口测定。在这份报告中，我们提供了额外的证据，转运蛋白可以直接与MS含蛋白质相互作用，也表明它可以介导进口全长hnRNPA1。此外，RAN或RAN结合蛋白被鉴定为这种新型核输入途径的第二蛋白组分。来自酿酒酵母的转运蛋白亲属可能作为额外的核转运受体。(C)出版社：Academic Press，Inc.
Many nuclear proteins are imported into the cell nucleus by the ''classical'' nuclear localization signal (NLS)-mediated import pathway. In this pathway, a sequence rich in basic residues in the protein interacts with a heterodimeric complex termed importin and this, along with the GTPase Ran, mediates nuclear import of the NLS-bearing protein. The heterogeneous nuclear ribonucleoprotein (hnRNP) Al protein contains a novel nuclear localization sequence, termed M9, that does not contain any clusters of basic residues. Very recently, we showed that M9 directs import into the nucleus by a novel protein import pathway distinct from the classical NLS pathway. A 90-kilodalton protein termed transportin was identified as a protein that specifically interacts with wild-type M9 but not transport-defective MS mutants. Transportin and an ATP-regenerating system were found to be necessary and sufficient for import of MS-containing proteins in an in vitro import assay. In this report, we provide additional evidence that transportin can interact directly with MS-containing proteins and also show that it can mediate import of full-length hnRNP A1. In addition, Ran, or a Ran-binding protein, is identified as a second protein component of this novel nuclear import pathway. Transportin relatives from Saccharomyces cerevisiae which likely serve as additional nuclear transport receptors are described. (C) 1996 Academic Press, Inc.