Mechanisms in COPII-Dependent Transport

项目摘要 分泌途径中的选择性蛋白质运输对细胞的功能和生长至关重要。我们的研究 计划的重点是依赖于涂层的分选机制，这种机制催化 内质网和高尔基复合体。在这里，新生的分泌蛋白在内质网被翻译 然后，完全折叠的蛋白质被选择性地包装到COPII包被的囊泡中，用于顺行运输 去高尔基建筑群。这条向前的通道被来自高尔基山脉的逆行运输所平衡，高尔基山脉 选择性地在COPI包被的囊泡中将蛋白质返回到内质网。确保只递送折叠的内分泌物 蛋白质，这一过程称为内质网质量控制，在内质网中保留新生的蛋白质，直到正确折叠或 最终以末端错误折叠的蛋白质为目标进行降解。协调高效排序的机制 使用ER质量控制的货物进入运输小囊的情况还不是很清楚。我们已经确定了一套 跨膜货物受体在衣物依赖的分选和质量中发挥重要作用 在早期分泌途径中的控制。这项研究提案将解决该领域的关键问题。 关于如何控制货物与受体的结合以实现蛋白质的净定向运输和 货物受体如何在ER质量控制中发挥作用。该提案的具体目的是：(1)确定 Erv41-Erv46货物受体如何催化修复逃逸的内质网驻留蛋白；(2)定义 识别Erv41-Erv46所需的货物中的分子信号；(3)研究Erv41-Erv46是如何- Erv46从ER后的隔室中检索错误折叠的蛋白质；以及(4)确定Erv26和Erv26如何 Erv29顺行受体在内质网质量控制中的作用我们将严格测试我们的假设 利用分子遗传学通过无细胞分析监测体内蛋白质功能的酵母模型 在体外用分离的内质网和高尔基膜，以及用纯化的因子进行重建实验。 确定这些基本细胞过程的分子机制应该得到改善 目前治疗与分泌途径功能有关的人类疾病的方法。

Project Summary Selective protein trafficking in the secretory pathway is vital for cell function and growth. Our research program is focused on coat-dependent sorting mechanisms that catalyze transport between the endoplasmic reticulum (ER) and Golgi complex. Here nascent secretory proteins are translated at the ER and then fully folded proteins are selectively packaged into COPII coated vesicles for anterograde transport to the Golgi complex. This forward pathway is balanced by retrograde transport from the Golgi, which selectively returns proteins to the ER in COPI coated vesicles. To ensure delivery of only folded secretory proteins, a process known as ER quality control retains nascent proteins in the ER until correctly folded or ultimately targets terminally misfolded proteins for degradation. Mechanisms that coordinate efficient sorting of cargo into transport vesicles with ER quality control are not well understood. We have identified a set of transmembrane cargo receptors that perform important functions in coat-dependent sorting and quality control in the early secretory pathway. This research proposal will address key questions in the field regarding how cargo binding to receptors is controlled to achieve net directional transport of proteins and how cargo receptors function in ER quality control. The specific aims of the proposal are to: (1) determine how the Erv41-Erv46 cargo receptor catalyzes retrieval of escaped ER resident proteins; (2) define molecular sorting signals in cargo that are required for Erv41-Erv46 recognition; (3) investigate how Erv41- Erv46 retrieves misfolded proteins from post-ER compartments; and (4) determine how the Erv26 and Erv29 anterograde cargo receptors function in ER quality control. We will rigorously test our hypotheses in a yeast model by exploiting molecular genetics to monitor protein function in vivo, through cell free assays with isolated ER and Golgi membranes in vitro and in reconstitution experiments with purified factors. Defining the molecular mechanisms that underlie these fundamental cellular processes should improve current approaches to treat human diseases connected to secretory pathway function.