RECOGNITION AND REMOVAL OF ALTERED MEMBRANE PROTEINS

识别和去除老化或异常的蛋白质对 细胞健康和长寿。培养中的细胞(活体细胞模型) 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的原因尚不清楚，但它可能比 异常蛋白质的积累(很可能是由于氧自由基 损害)使某些生化过程的特定活动减少到 低于某些重要细胞所需的阈值 功能。多细胞生物体(即人)的衰老只是一个 单个细胞与年龄相关的功能障碍的积分。以此类推 在细胞系统中，生命继续，直到细胞的活动 控制某些重要功能降至所需的阈值以下 维持整个有机体的内稳态。这一过程 细胞内异常蛋白的识别和去除是， 因此，在维持细胞活力方面极其重要，因此， 生物体作为一个整体的活力。然而，几乎没有什么是 已知细胞内蛋白质周转，特别是膜 蛋白质周转率。 这一建议解决了膜的生化机制的问题。 使用蛋白质周转的模型系统，最近由 首席调查员。这项工作的基本目标是： 确定活性氧物种相互作用的位置和机制 与膜蛋白结合 评估亲脂性抗氧化剂(即维生素E)预防 膜蛋白的损伤和改变 阐明年龄改变或年龄改变的识别的生化机制 生化改变的蛋白质 描述一种蚀变的去除和分解代谢的机制 膜蛋白。 细胞在不同氧浓度或不同温度下生长时蛋白质的周转 氚水的存在(以稳定单线态氧)将是 放射性同位素技术检测和一种新的、无损的 荧光法。因为先前显示蛋白质周转发生在 在离体膜中，外源添加抗氧化剂的效果 (亲脂性和亲水性)将进行测试。氧化改性 蛋白质中的残基将通过氨基酸分析进行鉴定，并 将采取循序渐进的净化程序，以确定 膜蛋白周转所需的蛋白质(和辅因子)。完成 这一项目应该构成生化的第一个描述 异常膜的识别和去除机制(S) 蛋白质。

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.