RAP AS A MOLECULAR CHAPERONE/ESCORT PROTEIN FOR LRP

RAP 作为 LRP 的分子伴侣/护航蛋白

• 批准号: 2439724
• 负责人: GUOJUN BU
• 金额: $ 26.45万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-01-01 至 2002-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2439724
• 关键词: X ray crystallography; binding proteins; laboratory mouse; low density lipoprotein receptor; molecular chaperones; protein structure function; protein transport; receptor mediated endocytosis; tissue /cell culture

The LDL receptor-related protein (LRP) is an extremely large (600,000 kDa) single chain protein with four related extracellular domains that are in turn composed of multiple (2, 8, 10, 11 respectively) cysteine-rich ligand binding repeats. LRP has emerged as a unique endocytic receptor due to its ability to bind and endocytose a number of structurally and functionally distinct ligands. These include apolipoprotein E, 2-macroglobulin, tPA, and urokinase-plasminogen activator. A 39kDa receptor-associated protein (RAP) co-purifies with intracellular LRP and blocks ligand binding to LRP in vitro. Preliminary data provided in this proposal demonstrate that the different ligands bind to multiple and distinct regions on LRP and LRP binding sites on RAP. In addition, many cells that synthesize LRP and RAP also synthesize ligands for the receptor, which can prevent the correct folding of LRP if they associate to early. The P.I. hypothesizes that RAP serves a chaperoning function in the folding and proper trafficking of LRP by binding it and preventing premature association with ligand. Experiments are proposed to elucidate the molecular mechanism by which RAP interacts with LRP, explore the structural features of RAP by solving its crystal structure, determine the role of RAP as a folding chaperone using in vivo and in vitro methods, and define the trafficking of RAP and LRP both as individual molecules and interacting complexes.

LDL 受体相关蛋白 (LRP) 非常大 (600,000 kDa) 具有四个相关胞外结构域的单链蛋白 由多个（分别为 2、8、10、11 个）富含半胱氨酸的配体组成 结合重复。 LRP 因其独特的内吞受体而成为一种独特的内吞受体。 结合和内吞许多结构和功能的能力 不同的配体。这些包括载脂蛋白 E、2-巨球蛋白、tPA、 和尿激酶纤溶酶原激活剂。 39kDa 受体相关蛋白 (RAP) 与细胞内 LRP 共纯化并阻断配体与 LRP 的结合 体外。本提案中提供的初步数据表明 不同的配体与 LRP 和 LRP 上的多个不同区域结合 RAP 上的结合位点。此外，许多合成LRP和RAP的细胞 还合成受体的配体，这可以阻止正确的 如果 LRP 与早期相关联，则折叠。 P.I.假设 RAP 在 LRP 的折叠和正确运输中发挥陪伴作用 通过结合它并防止与配体过早结合。 实验旨在阐明 RAP 的分子机制 与LRP相互作用，通过求解RAP的结构来探索RAP的结构特征 晶体结构，确定 RAP 作为折叠伴侣的作用 体内和体外方法，并定义 RAP 和 LRP 的运输 既作为单个分子又作为相互作用的复合物。