PROTEIN CARBOXYL METHYLATION IN BRAIN

大脑中的蛋白质羧基甲基化

• 批准号: 6187707
• 负责人: DANA WILLIAM ASWAD
• 金额: $ 22.77万
• 依托单位: UNIVERSITY OF CALIFORNIA-IRVINE
• 依托单位国家: 美国
• 财政年份: 1981
• 资助国家: 美国
• 起止时间: 1981-04-01 至 2002-03-21
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6187707
• 关键词: Escherichia coli; PC12 cells; brain metabolism; enzyme mechanism; enzyme substrate; gene expression; histones; in situ hybridization; laboratory rat; methyltransferase; posttranslational modifications; protein metabolism; protein purification; protein sequence; synapsins

DESCRIPTION (Adapted from applicant's abstract): The overall goal of this project is to elucidate the biological role of protein L-isoaspartyl methyltransferase (PIMT), a protein methylating enzyme that is enriched in brain and catalyzes selective methylation of atypical L-isoaspartyl residues. These unusual structures are characterized by an abnormal isopeptide bond in which an aspartyl residue is linked to its carboxyl-flanking neighbor via its side-chain beta-carboxyl group, rather than through the normal alpha-linkage. Isoaspartyl sites are believed to arise from spontaneous alterations of proteins during aging and/or from errors in protein synthesis. In vitro, PIMT has been demonstrated to catalyze isoaspartate repair by converting beta-linkage to normal alpha linkages. The aims of this continuation application are focused on two areas: characterization of several proteins which appear to be important targets of PIMT action in cells, and an attempt to demonstrate directly that PIMT functions as a repair enzyme in vivo. This will be accomplished by addressing 4 specific aims. The first will focus on histone H2B, a nuclear protein recently shown to undergo a selective and dramatic increase in isoaspartate content when PIMT activity is inhibited in rat PC12 cells. The second will involve the purification and characterization of a recently discovered high molecular weight methyl acceptor protein (HMAP) that is found only in brain and appears to have an unusually high content of isoaspartyl sites, as well as a high affinity for PIMT. The third specific aim is to determine if synapsin-1, a protein involved in regulating the availability of synaptic vesicles, forms isoaspartate in vivo. The final aim is to characterize an unusual isoaspartate-rich protein in E. coli that serves as an excellent substrate for rat brain PIMT. Together these investigations should provide important new insights into the significance of protein damage and repair systems in normal cell aging and in human disease.

描述（改编自申请人的摘要）：本项目的总体目标 该项目旨在阐明蛋白质 L-异天冬氨酰的生物学作用 甲基转移酶 (PIMT) 是一种蛋白质甲基化酶，富含 脑并催化非典型 L-异天冬氨酰的选择性甲基化 残留物。 这些不寻常的结构的特点是异常 异肽键，其中天冬氨酰残基与其相连 羧基侧翼邻居通过其侧链β-羧基，而不是 比通过正常的α-连接。 异天冬氨酰位点被认为 由衰老过程中蛋白质的自发改变和/或 蛋白质合成中的错误。 在体外，PIMT 已被证明可以 通过将 β 连接转化为正常 α 来催化异天冬氨酸修复 联系。 此延续申请的目标集中在两个方面 领域：几种似乎很重要的蛋白质的表征 细胞中 PIMT 作用的目标，并试图直接证明 PIMT 在体内起到修复酶的作用。 这将通过以下方式完成 解决 4 个具体目标。 第一个将重点关注组蛋白 H2B，一种核蛋白 最近显示蛋白质经历了选择性和显着的增加 当大鼠 PC12 细胞中 PIMT 活性受到抑制时，异天冬氨酸含量。 这 第二个将涉及最近的纯化和表征 发现了高分子量甲基受体蛋白（HMAP） 仅存在于大脑中，并且含量似乎异常高 异天冬氨酰位点，以及对 PIMT 的高亲和力。 第三具体 目的是确定突触蛋白-1（一种参与调节 突触小泡的可用性在体内形成异天冬氨酸。 决赛 目的是表征大肠杆菌中一种不寻常的富含异天冬氨酸的蛋白质，该蛋白质 作为大鼠脑 PIMT 的优良底物。 一起这些 调查应该提供重要的新见解 正常细胞衰老和人类中蛋白质损伤和修复系统的研究 疾病。