CELLULAR PROTEIN MATURATION AND DEGRADATION

这项建议的总体目标是了解生物 参与蛋白质折叠、质量控制和 膜糖蛋白酪氨酸酶的降解。酪氨酸酶是一种 黑色素合成所需的黑色素细胞专一性酶。基因突变 酪氨酸酶是黑色素所必需的一种黑素细胞特异性酶。 综合。酪氨酸酶基因突变是酪氨酸酶阴性的原因 白化病。这些突变形式中的许多都含有氨基酸替代 可能会降低正确折叠的效率和 导致内质网(ER)内滞留， 膜糖蛋白的蛋白质成熟。ER在其中的关键作用 酪氨酸的调节已在黑色素瘤中得到证实。 野生型酪氨酸酶内质网滞留导致随后 胞浆泛素依赖的蛋白酶体途径的降解。 了解酪氨酸酶的生物合成和 退化将有助于我们解决以下根本问题： 白化黑素细胞中的酪氨酸酶突变保留在内质网中吗？ 留存的机制是什么？这项保留是否可以免除为 产生一种定位正确且有功能的蛋白质？这种保留能不能 通过有选择地实施？ 这项建议的具体目的是：1)分析蛋白质 成熟(折叠、共翻译修饰和翻译后修饰，以及 伴侣结合)的野生型和突变型酪氨酸酶 无细胞成熟系统。2)组成ER- 酪氨酸酶在无细胞体系中的保留/降解途径 鉴定和鉴定参与分选和分离的蛋白质 退化过程。3)表征成熟度、品质 正常和恶性肿瘤中酪氨酸酶的控制和降解 黑素细胞。 这些研究将为成熟度、质量控制提供见解 酪氨酸酶的降解机制和致病机理 色素沉着相关的疾病。此外，更好地了解 细胞的生物合成和降解过程将有助于 针对遗传性疾病的靶向治疗药物设计 通常由贩运和内质网成熟缺陷以及白化病和/或 尤其是色素沉着过多。

The overall goal of this proposal is to understand the biological processes involved in the protein folding, quality control and degradation of the membrane glycoprotein tyrosinase. Tyrosinase is a melanocyte-specific enzyme required for melanin synthesis. Mutations in tyrosinase is a melanocyte-specific enzyme required for melanin synthesis. Mutations in tyrosinase are the cause of tyrosinase-negative albinism. Many of these mutated forms contain amino acid substitution that have the potential to reduce the efficiency of proper folding and to cause retention in the endoplasmic reticulum (ER), the site of protein maturation for membrane glycoproteins. The key role of the ER in the regulation of tyrosine has been demonstrated in a melanotic melanoma cells in which ER-retention of wild type tyrosinase leads to subsequent degradation by the cytosolic ubiquitin-dependent proteasomal pathway. Understanding the mechanisms involved in tyrosinase biosynthesis and degradation will help us to address the following fundamental questions: Are the tyrosinase-mutants in albino melanocytes retained in the ER? What is the mechanism of retention? Can this retention be relieved to produce a correctly localized and functional protein? Can this retention by selectively implemented? The specific aims of this proposal are: 1) To analyze the protein maturation (folding, co- and post-translational modification, and chaperone binding) of wild type and mutant forms of tyrosinase in a cell-free maturation system. 2) To constitute the ER- retention/degradation pathway of tyrosinase in a cell-free system, identify and characterize the proteins involved in both the sorting and degradation processes. 3) To characterize the maturation, quality control and degradation of tyrosinase in normal and malignant melanocytes. These studies will provide insights into the maturation, quality control and degradation mechanisms of tyrosinase and the etiology of pigmentation-related diseases. In addition, a better understanding of the biosynthetic and degradation processes of the cell would assist in the design of therapeutic drugs targeted against genetic diseases caused by trafficking and ER maturation defects in general, and albinism and/or hypo- and hyperpigmentation in particular.