Wilken N, Senécal J L, Scheer U, Dabauvalle M C
Department of Cell and Developmental Biology, Theodor-Boveri-Institute, University of Würzburg, Germany.
Eur J Cell Biol. 1995 Nov;68(3):211-9.
A partial cDNA clone coding for the mouse homologue of the human Ran-GTP binding protein, RanBP2, has been isolated by screening of a murine expression library with antibodies to nup180, a previously identified nuclear pore complex protein (nucleoporin). Whether the antibodies cross-reacted with the polypeptide encoded by the cDNA clone or, alternatively, nup180 is proteolytically related to RanBP2, has not been determined. The 3795-bp open reading frame of the cDNA encodes a polypeptide consisting of 1265 amino acids with three Ran-GTP binding domains (RanBD) that are almost identical with published partial amino acid sequences of human RanBP2 as deduced from several partial cDNA clones of other authors. Sequence analysis further revealed that murine RanBP2 contains tandemly repeated zinc fingers of Cys2-Cys2 type and multiple copies of the FXFG nucleoporin "signature" motif clustered in regions preceding the RanBDs. Antibodies raised against a synthetic peptide of the derived amino acid sequence decorated the cytoplasmic rings of nuclear pore complexes (NPCs) as shown by immunogold electron microscopy. We suggest that the cytoplasmically disposed nucleoporin RanBP2 provides docking sites for import substrate-receptor complexes and, further, that the affinity of these sites to the transport substrate is modulated in a Ran-dependent fashion.
通过用针对nup180（一种先前鉴定的核孔复合体蛋白，即核孔蛋白）的抗体筛选小鼠表达文库，分离出了编码人Ran-GTP结合蛋白RanBP2的小鼠同源物的部分cDNA克隆。尚未确定这些抗体是与cDNA克隆编码的多肽发生交叉反应，还是nup180与RanBP2存在蛋白水解相关性。该cDNA的3795个碱基对的开放阅读框编码一个由1265个氨基酸组成的多肽，该多肽具有三个Ran-GTP结合结构域（RanBD），与其他作者的几个部分cDNA克隆推导的已发表的人RanBP2部分氨基酸序列几乎相同。序列分析进一步表明，小鼠RanBP2含有串联重复的Cys2-Cys2型锌指，以及多个FXFG核孔蛋白“特征”基序的拷贝，这些基序聚集在RanBD之前的区域。免疫金电子显微镜显示，针对推导氨基酸序列的合成肽产生的抗体可修饰核孔复合体（NPC）的细胞质环。我们认为，位于细胞质中的核孔蛋白RanBP2为输入底物-受体复合物提供了停靠位点，并且进一步认为，这些位点与转运底物的亲和力以Ran依赖的方式受到调节。
