The Roles of Multiple Importins for Nuclear Import of Murine Aristaless-related Homeobox Protein
The Roles of Multiple Importins for Nuclear Import of Murine Aristaless-related Homeobox Protein
复制标题
多种导入蛋白对鼠无Aristaless相关同源框蛋白核导入的作用
DOI：
10.1074/jbc.m109.004242
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发表时间：
2009-07-24
影响因子：
4.8
通讯作者：
Tao, Tao
中科院分区：
文献类型：
--
作者：
Lin, Wenbo;Ye, Wenduo;Tao, Tao
具有核定位信号的蛋白质（NLS）的核输入是由穿梭载体（importins）介导的。一些货物显示出不止一个NLS，其中包括Arx等同源结构域蛋白，它对多种组织的发育至关重要。Arx有两个功能NLS。目前的研究表明，几种途径可以通过其NLS 2输入Arx，NLS 2位于其DNA结合同源结构域内。使用体外核输入试验，我们表明，进口的Arx通过NLS 2可以介导的输入蛋白β 1，输入蛋白9，或输入蛋白13，结合最强的输入蛋白β 1。所有结合对RanGTP敏感。基于精确结构域缺失的实验表明，NLS 2结合IMP β 1、IMP 9和IMP 13，并且包括输入蛋白结合亚结构域和具有对功能重要的精氨酸残基的调节亚结构域。此外，当NLS 2存在时，Arx可以与这些输入蛋白共沉淀。虽然Arx的核输入可以由这三种importin β介导，但从体内小干扰RNA消融和体外输入试验来看，importin β 1似乎起主要作用。这是首次证明importin β 1在配对同源结构域蛋白核输入中的作用。我们提出了一种新的和可能相当普遍的机制，核进口的配对型同源异型结构域蛋白，这是至关重要的发展。
Nuclear import of proteins with nuclear localization signals (NLSs) is mediated by shuttling carriers, the importins. Some cargoes display more than a single NLS, and among these are homeodomain proteins such as Arx, which is critical for development of multiple tissues. Arx has two functional NLSs. The present studies show that several pathways can import Arx via its NLS2, which is within its DNA binding homeodomain. Using an in vitro nuclear import assay, we show that import of Arx via NLS2 can be mediated by importin beta 1, importin 9, or importin 13, with binding being strongest to importin beta 1. All binding is sensitive to RanGTP. Experiments based on precise domain deletions indicate that NLS2 binds imp beta 1, imp9, and imp13 and includes both an importin binding subdomain and a regulatory subdomain with arginine residues being important for function. Moreover, Arx can be co-precipitated with these importins when NLS2 is present. Although nuclear import of Arx can be mediated by these three importin beta s, importin beta 1 seems to play the major role judging from in vivo small interfering RNA ablations and the in vitro import assay. This is the first evidence to show the role of importin beta 1 in nuclear import of paired-type homeodomain proteins. We propose a novel and possibly quite general mechanism for nuclear import of paired-type homeodomain proteins which is critical for development.