Kataoka N, Ohno M, Moda I, Shimura Y
Department of Biophysics, Faculty of Science, Kyoto University, Japan.
Nucleic Acids Res. 1995 Sep 25;23(18):3638-41. doi: 10.1093/nar/23.18.3638.
It has been shown that the monomethylated cap structure plays important roles in pre-mRNA splicing and nuclear export of RNA. As a candidate for the factor involved in these nuclear events we have previously purified an 80 kDa nuclear cap binding protein (NCBP) from a HeLa cell nuclear extract and isolated its full-length cDNA. In this report, in order to obtain a clue to the cellular functions of NCBP, we attempted to identify a factor(s) that interacts with NCBP. Using the yeast two-hybrid system we isolated three clones from a HeLa cell cDNA library. We designated the proteins encoded by these clones NIPs (NCBP interacting proteins). NIP1 and NIP2 have an RNP consensus-type RNA binding domain, whereas NIP3 contains a unique domain of Arg-Glu or Lys-Glu dipeptide repeats. We also show that NCBP requires NIP1 for binding to the cap structure. Possible roles of NIPs in cap-dependent nuclear processes are discussed.
研究表明，单甲基化帽结构在mRNA前体剪接和RNA的核输出中发挥重要作用。作为参与这些核事件的候选因子，我们之前从HeLa细胞核提取物中纯化了一种80 kDa的核帽结合蛋白（NCBP），并分离出其全长cDNA。在本报告中，为了获得有关NCBP细胞功能的线索，我们试图鉴定与NCBP相互作用的因子。利用酵母双杂交系统，我们从HeLa细胞cDNA文库中分离出三个克隆。我们将这些克隆编码的蛋白质命名为NIPs（NCBP相互作用蛋白）。NIP1和NIP2具有RNP共有型RNA结合结构域，而NIP3包含一个独特的精氨酸-谷氨酸或赖氨酸-谷氨酸二肽重复结构域。我们还表明，NCBP需要NIP1才能与帽结构结合。文中讨论了NIPs在帽依赖性核过程中的可能作用。
