Complex formation among the RNA export proteins Nup98, Rae1/Gle2, and TAP
Complex formation among the RNA export proteins Nup98, Rae1/Gle2, and TAP
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DOI：
10.1074/jbc.m302061200
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发表时间：
2003-06-06
影响因子：
4.8
通讯作者：
Powers, MA
中科院分区：
文献类型：
--
作者：
Blevins, MB;Smith, AM;Powers, MA
大多数通过核孔复合物的核质运输由输入/输出蛋白或核转运蛋白家族的可溶性受体介导。mRNA输出是独特的，因为该家族没有受体参与大部分mRNA的运输。相反，许多不同的蛋白质与mRNA输出有关，但一个包罗万象的模型仍然难以捉摸。了解这些蛋白质如何相互作用是开发这种模型的核心。在这里，我们集中在三个蛋白质之间的相互作用，涉及mRNA的输出，Nup 98，Rae 1/Gle 2，和TAP。我们已经定义了这些蛋白质之间形成的二元复合物。我们发现，Gle 2需要两个网站内TAP稳定的相互作用。引人注目的是，TAP对Nup 98的GLGG结构域内的特定区域具有最高的亲和力，而不是对所有核孔蛋白FG重复序列具有一般亲和力，这表明并非所有重复序列在功能上都是相同的。我们已经确定，三元复合物可以通过Gle 2和TAP同时结合到Nup 98上的相邻位点而形成。相比之下，Nup 98与TAP竞争Gle 2结合;当与Nup 98结合时，Gle 2不再与TAP直接相互作用。从这些相互作用中，我们提出Gle 2可能起到将TAP递送到Nup 98的作用，并且这可能代表出口复合物和核孔蛋白之间的一系列相互作用中的第一个。
Most nucleocytoplasmic traffic through the nuclear pore complex is mediated by soluble receptors of the importin/exportin or karyopherin family. mRNA export is unique in that no receptor of this family has been implicated in trafficking of the bulk of mRNAs. Instead, many diverse proteins have been linked to mRNA export, but an all-encompassing model remains elusive. Understanding how these proteins interact with each other is central to the development of such a model. Here, we have focused on the interactions between three proteins implicated in mRNA export, Nup98, Rae1/Gle2, and TAP. We have defined the binary complexes that form among these proteins. We find that Gle2 requires two sites within TAP for stable interaction. Strikingly, rather than a general affinity for all nucleoporin FG repeats, TAP has highest affinity for a specific region within the GLFG domain of Nup98, indicating that not all repeats are identical in function. We have established that the ternary complex can form through simultaneous binding of both Gle2 and TAP to adjacent sites on Nup98. In contrast, Nup98 competes with TAP for Gle2 binding; when bound to Nup98, Gle2 no longer interacts directly with TAP. From these interactions, we propose that Gle2 may act to deliver TAP to Nup98 and that this may represent the first in a series of interactions between an export complex and a nucleoporin.