Proteomic characterization of ubiquitin-dependent processes in the secretory pathway

这项研究计划旨在表征泛素系统的非蛋白分解功能，这些功能参与了维持分泌途径中的动态平衡。为此，我们计划纯化膜相关的CDC48蛋白复合体，并通过遗传和生化方法鉴定它们的功能。AAAATPase CDC48在哺乳动物中被称为p97或包含Valosin的蛋白(VCP)，在许多泛素依赖的过程中发挥关键作用，如同型膜融合、细胞周期控制、蛋白酶体介导的蛋白质降解和DNA修复。为了完成这些活动，CDC48/p97以一种时间和空间受控的方式与大量不同的辅助蛋白合作。值得注意的是，目前已知的绝大多数CDC48/p97辅助因子都含有泛素结合域或与泛素系统相连。然而，在大多数情况下，我们对它们的分子功能缺乏深入的了解。在这项工作中，我们计划分离新的CDC48相互作用蛋白，确定它们的功能，并建立一个CDC48辅助因子网络，将这种多功能的酶整合到分泌途径中特定的泛素依赖过程中。

This research proposal aims at characterizing non-proteolytic functions of the ubiquitin system that are involved in maintaining homeostasis in the secretory pathway. To this end we plan to purify mem-brane-associated Cdc48 containing protein complexes and identify their functions by genetic and biochemical methods. The AAAATPase Cdc48, in mammals termed p97 or “valosin containing protein” (VCP), is a key player in many ubiquitin-dependent processes like homeotypic membrane fusion, cell cycle control, proteasome-mediated protein degradation and DNA repair. To fulfill these activities, Cdc48/p97 teams up with a large set of diverse ancillary proteins in a temporally and spatially con-trolled manner. Notably, the vast majority of the presently known Cdc48/p97 co-factors contain ubiquitin binding domains or are elsewise linked to the ubiquitin system. However, in most cases we lack in depth knowledge on their molecular function. In the course of this work we plan to isolate novel Cdc48 interacting proteins, determine their function and establish a network of Cdc48 co-factors that integrates this versatile enzyme into particular ubiquitin-dependent processes in the secretory pathway.