PROTEIN CARBOXYL METHYLATION AND NEURONAL FUNCTION

蛋白质羧基甲基化与神经元功能

• 批准号: 3074924
• 负责人: DANA WILLIAM ASWAD
• 金额: $ 5.73万
• 依托单位: UNIVERSITY OF CALIFORNIA-IRVINE
• 依托单位国家: 美国
• 财政年份: 1986
• 资助国家: 美国
• 起止时间: 1986-03-01 至 1991-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3074924
• 关键词: Alzheimer's disease; Anura; aging; aspartate; brain cell; calcium; cyclic AMP; cyclic GMP; fresh water environment; laboratory rat; membrane proteins; myelin; neural information processing; neurochemistry; neurophysiology; neurotransmitter receptor; phosphatidylinositols; stimulus /response; synapses; synaptosomes

The overall goal of this project is to understand the role of protein carboxyl methylation in neuronal function. There are two current hypotheses of methylation function in eucaryotes: (1) that it mediates some aspect of stimulus-response coupling via the reversible modification of protein function, and (2) that it facilitates the repair or degradation of defective proteins which contain abnormal forms of aspartic acid. In testing the regulation hypothesis, we propose to measure the ability of certain neurotransmitters and depolarizing agents to stimulate transient protein methylation (as indicated by the evolution of radiolabeled methanol), to search in purified subfractions of brain for specific protein which serve as preferential substrates in an in vitro transient methylation assay, and, to determine if the in vitro transient methylation reaction is regulated by the second messengers cAMP, cGMP, Ca++ or phosphatidyl inositol. Our strategy in these experiments is derived from recent indications that carboxyl methylation may serve as an initial activation step in a more complex protein modification reaction than hitherto assumed. An alternative role for carboxyl methylation in the repair or degradatiom of damaged proteins is suggested by the recently discovered selectivity of the methyltransferase enzyme for proteins containing abnormal forms of aspartate, particularly L-isoaspartyl and D-aspartyl residues. We propose to determine if the methyl accepting substrates we have located in synaptic membranes and myelin are enriched in these atypical forms of aspartate, and, to determine if the levels of these abnormal proteins and/or the methyltransferase enzyme changes significantly with age in the human or in association with Alzheimer's disease. Establishing a firm role for carboxyl methylation should provide important new insight on fundamental mechanisms of cellular regulation and/or aging processes in the mammalian nervous system.

这个项目的总体目标是了解蛋白质的作用。 神经元功能中的羧甲基化。有两个水流 真核生物甲基化功能的假说：(1)它介导了一些 通过可逆修饰的刺激-反应耦合方面 蛋白质的功能，以及(2)它有助于修复或降解 含有异常形式天冬氨酸的有缺陷的蛋白质。在……里面 检验调节假说，我们建议测量的能力 某些神经递质和去极剂可刺激短暂性 蛋白质甲基化(如放射性标记的进化所示 甲醇)，在纯化的大脑亚组分中寻找特定的蛋白质 它们在体外瞬时甲基化中作为优先底物 检测，并确定体外瞬时甲基化反应是否 受第二信使cAMP、cGMP、Ca++或磷脂调节 肌醇。我们在这些实验中的策略是从最近 有迹象表明羧甲基化可能是一种初始激活 一种比以往更复杂的蛋白质修饰反应 假设如此。羧甲基化在修复或修复中的替代作用 最近发现的一项研究表明，受损蛋白质的降解 甲基转移酶对含蛋白质的选择性 天冬氨酸的异常形式，特别是L-异天冬氨酸和D-天冬氨酸 残留物。我们建议确定接受甲基的底物是否 位于突触膜上，髓鞘在这些 非典型形式的天冬氨酸，并确定这些物质的水平 异常蛋白质和/或甲基转移酶显著改变 随着人类年龄的增长或与阿尔茨海默病有关。 确立羧甲基化的坚实作用应该提供重要的 对细胞调节和/或衰老基本机制的新认识 哺乳动物神经系统中的过程。