CELLULAR PROTEIN MATURATION AND DEGRADATION

本提案的总体目标是了解生物学 涉及蛋白质折叠、质量控制和 膜糖蛋白酪氨酸酶的降解。酪氨酸酶是一种 黑色素细胞合成所需的特异性酶。突变 酪氨酸酶是黑素细胞特异性酶， 合成.酪氨酸酶突变是酪氨酸酶阴性的原因 白化病许多这些突变形式含有氨基酸取代 有可能降低正确折叠的效率， 引起内质网（ER）滞留，内质网是 膜糖蛋白的蛋白质成熟。急诊室的关键作用 酪氨酸调节已在黑色素性黑素瘤中得到证实 细胞，其中野生型酪氨酸酶的ER保留导致随后的 通过胞质泛素依赖性蛋白酶体途径降解。 了解酪氨酸酶生物合成的机制， 退化将有助于我们解决以下基本问题： 白化病黑素细胞中的酪氨酸酶突变体是否保留在ER中？ 保留的机制是什么？这种保留是否可以解除， 产生一个正确定位和功能的蛋白质？这种保留能不能 有选择地实施？ 具体目标是：1）分析蛋白质 成熟（折叠、共翻译和翻译后修饰，以及 伴侣结合）的酪氨酸酶的野生型和突变体形式在一个 无细胞成熟系统。2)为了建立急诊室- 酪氨酸酶在无细胞系统中的保留/降解途径， 鉴定和表征参与分选和 降解过程。3)为了表征成熟度、质量 正常和恶性肿瘤中酪氨酸酶的控制和降解 黑素细胞 这些研究将提供深入了解成熟，质量控制， 酪氨酸酶的降解机制和酪氨酸酶的病因学 色素沉着相关疾病。此外，更好地了解 细胞的生物合成和降解过程将有助于 设计针对遗传疾病的治疗药物， 通过一般的运输和ER成熟缺陷，以及白化病和/或 尤其是色素沉着不足和色素沉着过度。

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.