MOLECULAR CHAPERONES AND IG BIOSYNTHESIS

分子伴侣和 IG 生物合成

• 批准号: 6386315
• 负责人: Linda M Hendershot
• 金额: $ 28.33万
• 依托单位: ST. JUDE CHILDREN'S RESEARCH HOSPITAL
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-04-01 至 2004-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6386315
• 关键词: antibody formation; dogs; endoplasmic reticulum; immunoglobulin G; laboratory mouse; laboratory rabbit; molecular assembly /self assembly; molecular chaperones; protein binding; protein biosynthesis; protein folding; stress proteins; tissue /cell culture

DESCRIPTION (adapted from investigator's abstract): The normal development and function of the immune system is dependent, in part, on the proper assembly and expression of immunoglobulin (Ig) receptor and secreted proteins. Like all secretory pathway proteins, Ig molecules are synthesized, folded and assembled in the endoplasmic reticulum (ER), but unlike most heteromeric proteins, there is a developmental asymmetry in the expression of the subunits. The molecular chaperones of the ER play a critical role in controlling the folding of the individual subunits and ensuring that incompletely or improperly assembled Ig proteins do not leave this organelle. Therefore, elucidating the mechanisms by which Ig maturation in the ER is controlled is important to understanding how the proper development of the immune system is ensured. In the past, Ig heavy and light chains have also provided an excellent model system for identifying components of the ER quality control system and for understanding their function. During the last funding period, our studies revealed that Ig transport is controlled at the level of domain folding and that unlike other unfolded proteins, unassembled heavy chains do not appear to cycle on and off ER chaperones. To understand the cellular machinery that is responsible for this, experiments are proposed in the present application to 1) determine the role of GRP94 (a major ER chaperone of unknown function) in maintaining heavy chains in an unfolded state that is competent for assembly with light chains, 2) identify and characterize ER proteins that regulate the ATPase cycle of BiP, an ER chaperone, in order to understand why it remains stably bound to Ig heavy chains in the absence of light chain synthesis, and 3) isolate ER homologues of the DnaJ chaperone cofactor, which acts to aid and stabilize the binding of hsp70 chaperones to unfolded proteins to understand how BiP's binding to heavy chains is controlled. The data obtained from the experiments outlined in this proposal will increase our understanding of the ER quality control machinery that is so crucial to proper Ig biosynthesis and maturation.

描述（改编自研究者的摘要）：正常的发育和 免疫系统的功能部分取决于正确的组装和 免疫球蛋白 (Ig) 受体和分泌蛋白的表达。像所有人一样 分泌途径蛋白、Ig分子的合成、折叠和组装 在内质网 (ER) 中，但与大多数异聚蛋白不同， 是亚基表达的发育不对称。分子 ER 的分子伴侣在控制 ER 折叠方面发挥着关键作用 单个亚基并确保不完整或不正确组装的 Ig 蛋白质不会离开这个细胞器。因此，通过阐明机制 ER 中哪些 Ig 的成熟受到控制对于理解如何控制很重要 确保免疫系统的正常发育。以前，Ig重 轻链也为识别提供了一个优秀的模型系统 ER 质量控制系统的组成部分并了解其 功能。在上一个资助期间，我们的研究表明 Ig 传输是在域折叠级别进行控制的，这与其他方式不同 未折叠的蛋白质、未组装的重链似乎不会循环开启和关闭 急诊室监护人。了解负责的细胞机制 为此，在本申请中提出实验来1)确定 GRP94（功能未知的主要 ER 伴侣）在维持重度中的作用 处于展开状态的链能够与轻链组装， 2) 鉴定和表征调节 BiP ATP 酶循环的 ER 蛋白， ER 伴侣，以了解为什么它仍然与 Ig 重链稳定结合 链在没有轻链合成的情况下，并且3)分离ER同系物 DnaJ 伴侣辅助因子，其作用是帮助和稳定 hsp70 分子伴侣与未折叠蛋白的结合，以了解 BiP 如何与重链结合 链条受到控制。从本文概述的实验中获得的数据 该提案将增加我们对 ER 质量控制机制的了解 这对于正常的 Ig 生物合成和成熟至关重要。