Isolation and characterization of a protein participating in nucleotide excision repair in human cells.

紫外线损伤特异性结合蛋白被认为在紫外线照射的人细胞DNA修复的早期阶段起着重要作用。我们观察了与紫外线照射的DNA选择性结合的核蛋白和胞浆蛋白。我们从核提取物中纯化了一种与humo-2结合的蛋白，命名为NF-10。其分子量为~ 40 kDa。用对环丁烷嘧啶二聚体和（6-4）光产物特异的光解酶进行的实验表明，NF-10蛋白通过（6-4）光产物与UV-DNA结合，用针对NF-10蛋白的单克隆抗体进行的实验表明，NF-10蛋白在着色性干皮病互补组细胞系中均存在。提示NF-10是一种不同于XPA蛋白和UV-DNA结合因子的新蛋白。该蛋白的部分肽段序列与人甘油醛-3-磷酸脱氢酶（GAPD）序列几乎完全相同。纯化的NF-10蛋白具有糖酵解的GAPD活性。这些结果表明，GAPD可能在核苷酸切除修复以及糖酵解中发挥作用，可能在损伤识别过程中。

UV-damage-specific binding proteins are considered to play important roles in the early steps of DNA repair in human cells irradiated with UV.We have survayd the nuclear and cytoplasmic proteins binding selectively to UV-irradiated DNA.We purifiied one of the binding factors from nuclear extracts to humogeneity, which was designated NF-10. Its molecular weight is - 40kDa. The experimets using photolyases specific for cyclobutane pyrimidine dimer and (6-4) photoproduct revealed that the NF-10 protein binds to UV-DNA though (6-4) photoproducts.By using a monoclonal antibody raised against the NF-10 protein, we could show the existence of the NF-10 protein in all xeroderma pigmentosum complementation group cell lines. This result suggests us that NF-10 is a novel protein different from XPA protein and UV-DNA binding factor previously reported. The immunodepletion of NF-10 protein from cell extract by the antibody decreased the in vitro repair activity, whereas the additon of the protein recovered it.The partial peptide sequences of the protein are almost identical to human glyceraldehyde-3-phosphate dehydrogenase (GAPD). The purified NF-10 protein exerted the GAPD activuty in glycolysis. These results suggest that the GAPD may play a function in nucleotide excision repair as well as in glycolysis, probably in the damage recognition process.