FUNCTIONAL ANALYSIS OF RAD23 PROTEIN

我们发现DNA修复蛋白RAD23具有蛋白水解性 功能。这里提出的研究与辐射有广泛的相关性。 生物学，并能对分子的理解做出重大贡献 从酵母到人类的核苷酸切除-修复。 泛素/蛋白小体途径是许多关键蛋白降解所必需的 真核细胞中的调节器。这条途径的目标包括重要的 细胞周期调节因子、转录因子、肿瘤抑制因子和 信号传导分子。我们的初步发现揭示了 核苷酸切除-修复过程中的蛋白质降解；i)我们发现RAD23具有 蛋白分解功能。Ii)Rad 23被Rad53激酶磷酸化，它 调节DNA损伤诱导的检查点。三)特定泛素结合 (E2)酶，包括DNA修复蛋白Rad6，与 蛋白质小体。这些研究为研究人类免疫缺陷的作用奠定了坚实的基础 DNA修复中的蛋白质降解。 本拨款申请中提出的问题可以产生新的和 关于RAD23蛋白分解功能的有趣信息。这些研究可以 也增加了我们对底物靶向机制的理解，以及 E2/蛋白酶体相互作用的意义。其后果是 RAD23/蛋白酶体在DNA修复中的相互作用将被研究。 我们的研究增加了意义，因为RAD23的人类同源物是 在功能上类似于它们的酵母对应物。一个潜在的缺陷 几种人类疾病，包括着色性干皮病和Cockayne病 综合征，涉及核苷酸切除-修复途径。现在 对核苷酸切除-修复和泛素介导的蛋白降解的理解 得到了很好的发展，我们现在有能力形成一个连贯的模型 描述了这两条路径之间的联系。

We have discovered that the DNA repair protein Rad23 has a proteolytic function. The studies proposed here have broad relevance to radiation biology, and can make a strong contribution to a molecular understanding of nucleotide excision-repair from yeast to humans. The ubiquitin/proteosome pathway is required for the degradation of many key regulators in eukaryotic cells. The targets of this pathway include important cell-cycle regulators, transcription factors, tumor suppressors, and signal-transducing molecules. Our preliminary findings revealed a role for protein degradation in nucleotide excision-repair; i) we found that Rad23 has a proteolytic function. ii) Rad 23 is phosphorylated by the Rad53 kinase, which mediates a DNA damage-inducible checkpoint. iii) Specific ubiquitin-conjugating (E2) enzymes, including the DNA repair protein Rad6, interact with the proteosome. These studies provide a strong foundation for studying the role of protein degradation in DNA repair. The questions that are addressed in this Grant Application can yield new and interesting information on the proteolytic function of Rad23. These studies can also increase our understanding of the mechanisms of substrate targeting, and the significance of E2/proteasome interaction. The consequence of Rad23/proteasome interaction in DNA repair will be investigated. Our studies have added significance because the human homologs of Rad23 are functionally similar to their yeast counterpart. An underlying defect in several human diseases, including xeroderma pigmentosum and Cockayne's syndrome, involves the nucleotide excision-repair pathway. The present understanding of nucleotide excision-repair and ubiquitin-mediated proteolysis is well developed, and we now have the ability to form a coherent model that describes the link between these two pathways.