POST-TRANSLATIONAL REGULATION OF APOLIPOPROTEIN B

载脂蛋白 B 的翻译后调控

• 批准号: 3046586
• 负责人: Michael S Marks
• 金额: $ 2.76万
• 依托单位: U.S. NATIONAL INSTITUTES OF HEALTH
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-10-15 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3046586
• 关键词: abetalipoproteinemias; apolipoproteins; chimeric proteins; clone cells; endoplasmic reticulum; genetic manipulation; posttranslational modifications; protein degradation; transfection

Apolipoprotein B (apoB) is a major protein constituent of lipoproteins secreted by the liver and intestine. Newly synthesized apoB may be either fully translocated across the endoplasmic reticulum (ER) membrane, resulting in a form that is assembled into lipoprotein complexes and secreted, or incompletely translocated, resulting in a transmembrane form that is rapidly proteolyzed by an ER-associated degradation pathway. Exogenous factors affect the relative levels of secreted and degraded apoB in hepatocytes. In addition, unregulated degradation may be responsible for the absence of serum apoB in patients with abetalipoproteinemia. The goal of this proposal is to analyze structural, mechanistic, and regulatory features of apoB degradation in order to better understand the ER degradative pathway and the pathogenesis of abetalipoproteinemia. The structural determinants that target apoB to be degraded will be defined by analyzing the degradation of genetically engineered polypeptides expressed in transfectants of hepatoma cell line. Serially C-terminally deleted apoB forms and chimeric proteins consisting of relevant apoB segments fused to an indicator protein will be analyzed. Once these determinants are defined, the mechanisms underlying degradation will be addressed by analyzing proteins that associate with these determinants and by measuring the effects of metabolic inhibitors on degradation. Lastly, the regulation of apoB degradation by exogenous factors and its tissue specificity will be assessed, with particular emphasis on the fate of apoB in a cell line derived from a patient with abetalipoproteinemia.

载脂蛋白 B (apoB) 是脂蛋白的主要蛋白质成分 由肝脏和肠道分泌。 新合成的 apoB 可能是 完全易位穿过内质网（ER）膜， 产生组装成脂蛋白复合物的形式， 分泌或不完全易位，导致跨膜形式 它被 ER 相关降解途径快速蛋白水解。 外源因素影响apoB分泌和降解的相对水平 在肝细胞中。 此外，不受控制的降解可能是造成这种情况的原因。 用于无β脂蛋白血症患者血清apoB的缺失。 这 该提案的目标是分析结构、机制和监管 apoB 降解的特征，以便更好地了解 ER 降解途径和无β脂蛋白血症的发病机制。 这 以 apoB 为目标进行降解的结构决定因素将定义为 分析表达的基因工程多肽的降解 在肝癌细胞系的转染子中。 C 端连续删除的 apoB 形式和由融合相关 apoB 片段组成的嵌合蛋白 将分析指示蛋白。 一旦这些决定因素 定义，退化的潜在机制将通过以下方式解决 分析与这些决定因素相关的蛋白质并通过测量 代谢抑制剂对降解的影响。 最后，规定 外源因素对 apoB 降解的影响及其组织特异性 评估，特别强调 apoB 在细胞系中的命运 来自患有无β脂蛋白血症的患者。