RECOGNITION AND REMOVAL OF ALTERED MEMBRANE PROTEINS

识别和去除老化或异常蛋白质对于 细胞健康和长寿。 培养细胞（体内细胞模型） 在停止复制之前表现出最大寿命潜力（MLSP）， 除非发生恶性转化导致永生 虽然有限MLSP的原因是未知的，但它可能比一个 异常蛋白质的积累（最可能是由于氧自由基 损害）减少某些生化过程的特定活动， 低于一些重要的细胞功能所需的阈值水平， 功能 多细胞生物体的衰老（即，男人）只是一个 个体细胞的年龄相关功能障碍的整体。 类似 在细胞系统中，生命一直持续到细胞的活动 控制某些重要功能下降到所需的阈值水平以下， 维持整个机体的内环境稳定。 的过程 识别和去除细胞内的异常蛋白质， 因此，在维持细胞活力方面非常重要，因此， 整个有机体的生命力。 然而，很少有 已知细胞内蛋白质周转，特别是膜 蛋白质周转 这一建议解决了膜的生化机制的问题 蛋白质周转使用模型系统最近的特点是 首席调查员 这项工作的基本目标是： 确定活性氧相互作用的位点和机制 一种膜蛋白 评估亲脂性抗氧化剂的功效（即，维生素E）预防 膜蛋白的损伤和改变 阐明识别年龄改变或 生化改变蛋白 描述一种改变的 膜蛋白 在不同氧浓度下生长的细胞中的蛋白质周转， 氘化水的存在（以稳定单线态氧）将 通过放射性同位素技术和一种新的非破坏性的 荧光法 由于蛋白质周转以前被证明发生 在隔离膜中， (both亲脂性和亲水性）进行测试。 氧化改性的 蛋白质中的残基将通过氨基酸分析鉴定， 将进行逐步纯化程序，以确定 膜蛋白周转所需的蛋白质（和辅因子）。 完成 这个项目的第一个描述应该是生物化学 参与识别和清除异常膜的机制 proteins.

The recognition and removal of aged or aberrant proteins is vital to cellular health and longevity. Cells in culture (models of cells in vivo) exhibit a maximum life span potential (MLSP) before ceasing to replicate, unless a malignant transformation occurs resulting in immortality. Although the cause of the finite MLSP is unknown, it is possible than an accumulation of aberrant proteins (most likely due to oxygen radical damage) reduces the specific activities of certain biochemical processes to below a threshold level required for the performance of some vital cellular function. Aging of a multicellular organism (i.e., man) is simply an integral of the age-related dysfunction of individual cells. In analogy with the cellular system, life continues until the activity of cells controlling some vital function drops below a threshold level required to sustain the homeostasis of the whole organism. The processes of recognition and removal of aberrant proteins within the cell are, therefore, extremely important in maintaining cellular vitality and, hence, the vitality of the organism as a whole. Nevertheless, very little is known about intracellular protein turnover, and in particular, membrane protein turnover. This proposal addresses the question of biochemical mechanisms of membrane protein turnover using a model system recently characterized by the principal investigator. The fundamental goals of the work are to: Identify sites and mechanisms of the interaction of active oxygen species with a membrane protein Assess the efficacy of lipophilic antioxidants (i.e., Vitamin E) to prevent the damage and alteration of membrane proteins Elucidate the biochemical mechanisms of recognition of an age-altered or biochemically-altered protein Characterize the mechanisms of removal and catabolism of an altered membrane protein. Protein turnover in cells grown under various oxygen concentrations or in the presence of deuterated water (to stabilize singlet oxygen) will be assayed by radioisotopic techniques and a novel, nondestructive fluorescence method. Since protein turnover was previously shown to occur in isolated membranes, the effects of extrinsically added antioxidants (both lipophilic and hydrophilic) will be tested. The oxidatively modified residues in the protein will be identified by amino acid analysis, and a step-by-step purification procedure will be undertaken to identify the protein (and cofactors) required for membrane protein turnover. Completion of this project should constitute the first description of the biochemical mechanism(s) involved in the recognition and removal of aberrant membrane proteins.