CONTROL OF EUCARYOTIC MEMBRANE FUNCTION BY METHYLATION

通过甲基化控制真核细胞膜功能

• 批准号: 3273504
• 负责人: STEVEN G CLARKE
• 金额: $ 24.61万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 1978
• 资助国家: 美国
• 起止时间: 1978-12-01 至 1991-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3273504
• 关键词: Escherichia coli; S adenosylmethionine; aspartate; cell growth regulation; cytoskeleton; enzyme mechanism; enzyme substrate; erythrocyte membrane; erythrocytes; gel electrophoresis; human tissue; membrane permeability; membrane proteins; methylation; molecular site; peptide chemical synthesis; protein biosynthesis; protein metabolism; protein structure; radiotracer; sickle cell anemia; tissue /cell culture

The objective of this proposal is to understand the physiological significance of an enzymatic methylation reaction which appears to be a step in the metabolism of altered intracellular proteins. This ubiquitous enzymatic activity catalyzes the S- adenosylmethionine-dependent methyl esterification of isomerized and racemized aspartic acid residues in a wide variety of membrane and cytosolic proteins. Normally functional L- aspartyl and L-asparaginyl residues can be altered by spontaneous aging and/or damage reactions to form D-aspartyl residues and L- isoaspartyl transpeptidation products. Proteins containing these latter residues may not be expected to be fully functional, and we are interested in pursuing the possibility that the enzymatic methylation of these proteins may lead to their repair and/or degradation. Since the chemical deterioration, replacement, or repair of various macromolecules is likely to be a major determinant in the aging process of an organism, understanding the role of these reactions may contribute significantly to our concepts of the stability of cellular physiological systems over extended periods of time. We propose to concentrate our efforts on the methylation of abnormal proteins in the human erythrocyte system, where the absence of protein synthesis simplifies the experimental design. Although previous work has shown that similar methylation reactions occur in other mammalian tissues, differences in the metabolism of the methylated proteins may exist and we will be interested in comparing these reactions in non-erythroid tissues. Our specific goals in this project period include furthering our understanding of the enzymology of protein carboxyl methyltransferases, characterizing the specific sites of methylation on membrane and cytosolic proteins in the cell, and delineating the various possible pathways for the metabolism of methylated proteins. We will continue to use synthetic peptides as models for the methylated and demethylation reactions. Our long term goal will be to understand the functional role of protein covalent modification reactions that are involved in the repair and/or specific degradation of cellular proteins.

这项提案的目的是了解生理 酶促甲基化反应的重要性， 是改变细胞内蛋白质代谢的一个步骤。 这种普遍存在的酶活性催化S- 腺苷甲硫氨酸依赖性甲酯化 异构化和外消旋化的天冬氨酸残基， 膜蛋白和胞质蛋白。 正常功能L- 天冬酰胺酰基和L-天冬酰胺酰基残基可以通过自发的 老化和/或损伤反应，形成D-乙酰基残基和L-乙酰基残基。 异戊酰基转肽产物。 含有这些的蛋白质 后一种残基可能不具有完全的功能，我们 有兴趣探索酶促反应 这些蛋白质的甲基化可以导致它们的修复和/或 降解 由于化学变质、更换或 各种大分子的修复可能是一个主要的 决定生物体衰老过程的因素， 这些反应的作用可能对我们的 细胞生理系统稳定性的概念， 很长时间 我们建议将我们的努力集中在甲基化 人体红细胞系统中的异常蛋白质， 没有蛋白质合成简化了实验设计。 虽然之前的研究表明，类似的甲基化 反应发生在其他哺乳动物组织中， 甲基化蛋白质的代谢可能存在，我们将 感兴趣的是在非红细胞组织中比较这些反应。 我们在这个项目期间的具体目标包括进一步促进我们的 对蛋白质羧基酶学的认识 甲基转移酶，其特征在于 - 细胞中膜和胞质蛋白上的甲基化，和 描绘了各种可能的代谢途径， 甲基化蛋白质。 我们将继续使用合成肽 作为甲基化和去甲基化反应的模型。 我们 长期目标将是了解蛋白质的功能作用 参与修复的共价修饰反应 和/或细胞蛋白质的特异性降解。