Differential modes of nuclear localization signal (NLS) recognition by three distinct classes of NLS receptors
Differential modes of nuclear localization signal (NLS) recognition by three distinct classes of NLS receptors
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DOI：
10.1074/jbc.272.42.26375
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发表时间：
1997-10-17
影响因子：
4.8
通讯作者：
Yoneda, Y
中科院分区：
文献类型：
--
作者：
Miyamoto, Y;Imamoto, N;Yoneda, Y
核定位信号（NLS）与核孔靶向复合物的形成介导了嗜核蛋白对核孔的靶向作用。最近，一个新的人类蛋白质，Qip 1，从酵母双杂交系统与DNA解旋酶Q1的鉴定。这项研究表明，Qip 1是一种新的第三类NLS受体，有效地识别解旋酶Q1的NLS。此外，在这项研究中获得的数据表明，Qip 1和解旋酶Q1的NLS之间的特异性相互作用需要其最小必需NLS的上游序列。通过在毛地黄皂苷透化的无细胞转运系统中单独使用纯化的重组蛋白，证明了两种已知的人NLS受体Rch 1和NPI-1能够将所有测试的NLS底物转运到细胞核中，而Qip 1最有效地转运解旋酶Q1-NLS底物，其包含我们迄今为止检查的系统的上游序列。此外，在HeLa细胞粗胞质溶胶中，发现内源性Rch 1与所有测试的NLS底物结合，而内源性NPI-1的结合仅限于一些NLS，尽管事实上NPI-1本身显示出与多种NLS的结合活性。这些结果表明，至少有三个结构和功能不同的NLS受体存在于人类单细胞群体中，并表明，核输入的亲核蛋白可以控制在一个复杂的方式在NLS识别步骤的各种NLS受体的存在，每个NLS的各种特异性。
The targeting of karyophilic proteins to nuclear pores is mediated via the formation of a nuclear pore-targeting complex, through the interaction of nuclear localization signal (NLS) with its NLS receptor. Recently, a novel human protein, Qip1, was identified from a yeast two-hybrid system with DNA helicase Q1. This study demonstrates that Qip1 is a novel third class of NLS receptor that efficiently recognizes the NLS of the helicase Q1. Moreover, the data obtained in this study show that the specific interaction between Qip1 and the NLS of the helicase Q1 requires its upstream sequence of the minimal essential NLS. By using purified recombinant proteins alone in the digitonin-permeabilized cell-free transport system, it was demonstrated that the two known human NLS receptors, Rch1 and NPI-1, are able to transport all the tested NLS substrates into the nucleus, while Qip1 most efficiently transports the helicase Q1-NLS substrates, which contain its upstream sequence in so far as we have examined the system. Furthermore, in HeLa cell crude cytosol, it was found that endogenous Rch1 binds to all the tested NLS substrates, while the binding of endogenous NPI-1 is restricted to only some NLSs, despite the fact that NPI-1 itself shows binding activity to a variety of NLSs. These results indicate that at least three structurally and functionally distinct NLS receptors exist in the human single cell population, and suggest that the nuclear import of karyophilic proteins may be controlled in a complex manner at the NLS recognition step by the existence of a variety of NLS receptors with various specificities to each NLS.