FUNCTIONAL ASPECTS OF THE MULTICATALYTIC PROTEINASE COMP

多催化酶复合体(MPC)，也被称为 蛋白酶体，是一个高分子质量(约700 kDa) 由28至32个低分子质量亚基组成的胞内颗粒 (22至34 kDa)，其中13个不相同。货币政策委员会的重要性 对于基本细胞功能的研究表明它是 在所有真核细胞中都存在，它在 进化，它参与了抗原的处理，它 构成泛素依赖途径的“蛋白分解核心” 对于细胞内的蛋白水解酶来说，它是细胞不可缺少的 生存和繁殖。MPC表达的变化有 与恶性肿瘤的病理生理学有关，以及 在患者的血清中发现了抗MPC的自身抗体 系统性红斑狼疮。货币政策委员会展示了三个不同的 蛋白水解性裂解羧基侧肽的活性 碱性、酸性和疏水性氨基酸残基，均对 一般丝氨酸3，4-二氯异香豆素(DCI)的灭活 蛋白酶抑制剂。我们最近发现了第四种耐DCI病毒 裂解支链羧基一侧的肽键的成分 链氨基酸，并构成降解的一个主要因素 蛋白质和天然多肽。这个实验室的主要目标是 确定MPC的哪些亚基和多少亚基是 蛋白水解性，鉴定其特异性和蛋白水解性 机制，以检查调节蛋白分解活性的因素 并合成可用作探针的特定抑制剂 该复合体在细胞功能中的作用的研究。的目标是 这项建议是：1)评估特异度和调节 第四，抗DCI组分的活性，2)以确定是否 最近发现的脯氨酸氨基肽酶活性表达为 MPG的一种新成分，如果是这样的话，研究其性质 和专一性，3)确定最近发现的一个脯氨基- 内肽酶活性是由一个独特的成分引起的，如果是这样的话 检查其属性和特异性，4)调查 一组多肽的结构要求和动力学 激活MPC，5)检查完好细胞中MPC的功能 通过研究特异性抑制剂对细胞内蛋白的影响 对降解和细胞增殖的影响。

The multicatalytic proteinase complex (MPC), also referred to as the proteasome, is a high molecular mass (approximately 700 kDa) intracellular particle composed of 28 to 32 low molecular mass subunits (22 to 34 kDa) of which 13 are nonidentical. The importance of the MPC for fundamental cell functions is indicated by the finding that it is present in all eukaryotic cells, that it is highly conserved in evolution, that it is involved in antigen processing, that it constitutes the 'proteolytic core' of the ubiquitin-dependent pathway for intracellular proteolysls and that it is indispensable for cell survival and proliferation. Changes in the expression of the MPC have been implicated in the pathophysiology of malignancies, and autoantibodies against the MPC have been found in serum of patients with systemic lupus erythematosus. The MPC exhibits three distinct proteolytic activities cleaving peptide bonds on the carboxyl side of basic, acid and hydrophobic amino acid residues, all sensitive to inactivation by 3,4-dichloroisocoumarin (DCI), a general serine protease inhibitor. We have recently identified a fourth, DCI resistant component that cleaves peptide bonds on the carboxyl side of branched chain amino acids, and constitutes a major factor in the degradation of proteins and natural peptides. Major goals of this laboratory are to determine which and how many of the subunits of the MPC are proteolytically active, to identify their specificity and proteolytic mechanism, to examine factors that regulate the proteolytic activity and to synthesize specific inhibitors that could be used as probes in studies on the role of the complex in cellular functions. The aims of this proposal are: 1) to evaluate the specificity and regulation of activity of the fourth, DCI resistant component, 2) to determine if a recently identified prolyl aminopeptidase-like activity is expressed by a novel component of the MPG, and if so to investigate its properties and specificity, 3) to determine if a recently identified prolyl- endopeptidase-like activity is due to a unique component, and if so to examine its properties and specificity, 4) to investigate the structural requirements and kinetics of a group of peptides that activate the MPC, 5) to examine the function of the MPC in intact cells by studying the effect of specific inhibitors on intracellular protein degradation and on cell proliferation.