Nuclear localization of Rad51B is independent of Rad51C and BRCA2
Nuclear localization of Rad51B is independent of Rad51C and BRCA2
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DOI：
10.1093/mutage/gei011
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发表时间：
2005-01-01
期刊：
影响因子：
2.7
通讯作者：
Albala, JS
中科院分区：
文献类型：
--
作者：
Miller, KA;Hinz, JM;Albala, JS
Rad 51 B是人类Rad 51的五种旁系同源物之一，并且与另外三种Rad 51旁系同源物Rad 51 C、Rad 51 D和Xrcc 2在多蛋白复合物中发现。Rad 51 B参与该复合物取决于其与Rad 51 C的直接相互作用。在HeLa S3细胞中的EGFP-Rad 51 B融合蛋白的检测和在几种人细胞系中的免疫荧光显示Rad 51 B的核定位。Rad 51 B的N-末端KKLK基序（氨基酸4-7）中的突变导致Rad 51 B的细胞质定位，表明KKLK序列是Rad 51 B蛋白的核定位信号（NLS）。在缺乏Rad 51 C的仓鼠irs 3突变细胞中对野生型EGFP-Rad 51 B融合蛋白的检查表明，Rad 51 B独立于Rad 51 C定位于细胞核，Rad 51 C是Rad 51 B唯一已知的直接结合伴侣。利用BRCA 2突变细胞系CAPAN-1，表明Rad 51 B也定位于细胞核独立于BRCA 2。虽然Rad 51 B和BRCA 2都明显参与同源重组修复途径，但Rad 51 B和BRCA 2似乎不相关。这项研究发现，在Rad 51 B的N-末端的KKLK基序作为一个NLS，允许Rad 51 B定位到细胞核的Rad 51 C或BRCA 2独立。
Rad51B is one of the five paralogs of human Rad51 and is found in a multiprotein complex with three other Rad51 paralogs, Rad51C, Rad51D and Xrcc2. Participation of Rad51B in this complex depends on its direct interaction with Rad51C. Examination of EGFP-Rad51B fusion protein in HeLa S3 cells and immunofluorescence in several human cell lines reveal the nuclear localization of Rad51B. Mutations in the N-terminal KKLK motif of Rad51B (amino acids 4-7), result in the cytoplasmic localization of Rad51B suggesting that the KKLK sequence is the nuclear localization signal (NLS) for the Rad51B protein. Examination of wild-type EGFP-Rad51B fusion protein in hamster irs3 mutant cells, deficient in Rad51C, showed that Rad51B localizes to the nucleus independently of Rad51C, the only known direct binding partner for Rad51B. Utilization of a BRCA2 mutant cell line, CAPAN-1, showed that Rad51B also localizes to the nucleus independent of BRCA2. Although both Rad51B and BRCA2 are clearly involved in the homologous recombinational repair pathway, Rad51B and BRCA2 do not appear to associate. This study finds that a KKLK motif in the N-terminus of Rad51B serves as an NLS that allows Rad51B to localize to the nucleus independent of Rad51C or BRCA2.