Park C H, Bessho T, Matsunaga T, Sancar A
Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill 27599, USA.
J Biol Chem. 1995 Sep 29;270(39):22657-60. doi: 10.1074/jbc.270.39.22657.
A complex, which consists of ERCC1 (38 kDa) and a 112-kDa protein, was purified from HeLa cells to homogeneity. This complex complemented the nucleotide excision repair defects of rodent ERCC-1, ERCC-4, and human XP-F mutant cell-free extracts, indicating that the 112-kDa protein is XPF/ERCC4 and providing direct biochemical evidence that XPF and ERCC4 are identical. The XPF/ERCC4-ERCC1 complex has an endonuclease activity with preference for single-stranded DNA and a single-stranded region of duplex DNA with a "bubble" structure. This complex also nicks supercoiled DNA weakly, and this nicking activity is stimulated by human replication protein A when the DNA contains UV damage.
从HeLa细胞中纯化出一种由ERCC1（38 kDa）和一种112 kDa蛋白质组成的复合物，使其达到同质状态。该复合物弥补了啮齿动物ERCC - 1、ERCC - 4以及人类XP - F突变体无细胞提取物中的核苷酸切除修复缺陷，这表明112 kDa蛋白质是XPF/ERCC4，并提供了XPF和ERCC4相同的直接生化证据。XPF/ERCC4 - ERCC1复合物具有内切核酸酶活性，优先作用于单链DNA以及具有“气泡”结构的双链DNA单链区域。该复合物也能微弱地切割超螺旋DNA，当DNA含有紫外线损伤时，人类复制蛋白A会刺激这种切割活性。
