Hawryluk-Gara Lisa A, Platani Melpomeni, Santarella Rachel, Wozniak Richard W, Mattaj Iain W
Department of Cell Biology, University of Alberta, Edmonton, AB, Canada.
Mol Biol Cell. 2008 Apr;19(4):1753-62. doi: 10.1091/mbc.e07-08-0820. Epub 2008 Feb 6.
Transport across the nuclear envelope (NE) is mediated by nuclear pore complexes (NPCs). These structures are composed of various subcomplexes of proteins that are each present in multiple copies and together establish the eightfold symmetry of the NPC. One evolutionarily conserved subcomplex of the NPC contains the nucleoporins Nup53 and Nup155. Using truncation analysis, we have defined regions of Nup53 that bind to neighboring nucleoporins as well as those domains that target Nup53 to the NPC in vivo. Using this information, we investigated the role of Nup53 in NE and NPC assembly using Xenopus egg extracts. We show that both events require Nup53. Importantly, the analysis of Nup53 fragments revealed that the assembly activity of Nup53 depleted extracts could be reconstituted using a region of Nup53 that binds specifically to its interacting partner Nup155. On the basis of these results, we propose that the formation of a Nup53-Nup155 complex plays a critical role in the processes of NPC and NE assembly.
穿过核膜（NE）的运输由核孔复合体（NPC）介导。这些结构由多种蛋白质亚复合体组成，每种亚复合体都有多个拷贝，共同构成了NPC的八重对称性。NPC的一个进化保守亚复合体包含核孔蛋白Nup53和Nup155。通过截短分析，我们确定了Nup53中与相邻核孔蛋白结合的区域，以及在体内将Nup53靶向NPC的那些结构域。利用这些信息，我们使用非洲爪蟾卵提取物研究了Nup53在NE和NPC组装中的作用。我们发现这两个过程都需要Nup53。重要的是，对Nup53片段的分析表明，使用Nup53中与相互作用伴侣Nup155特异性结合的区域，可以重建Nup53缺失提取物的组装活性。基于这些结果，我们提出Nup53-Nup155复合体的形成在NPC和NE组装过程中起关键作用。
