Structure and function of the APC

描述(申请人提供)：细胞周期的进展由大量调节蛋白的周期性合成和降解控制。细胞周期调节的蛋白质降解是通过用泛素修饰蛋白质来完成的，然后泛素将这些蛋白质靶向蛋白质小体。泛素的加成是由一类称为泛素连接酶的酶完成的。调节细胞周期进程的最重要的泛素连接酶之一被称为后期促进复合体(APC)。虽然许多泛素连接酶是单体酶，但APC是一个由13个亚基组成的复合体，几乎所有的亚基在所有真核生物中都是保守的。除了这个核心催化复合体外，APC还与两种特异性因子中的任何一种相关，称为CDC20和CDH1。这些蛋白质被认为是APC与其底物相互作用的中介。任何必需的APC亚基的丢失都会导致细胞周期停滞于中期。值得注意的是，如果两个重要的APC靶点缺失/被抑制，任何正常必需的APC基因都可以被缺失：Securin(PDS L)和B型细胞周期蛋白/CDK复合体。除了提供有关APC在细胞分裂中的功能的有价值的信息外，这项工作还为研究APC的酶学和调控提供了一个新的工具。在这种菌株中，我们能够以在野生型背景下致命的方式修改APC复合体。这项建议概述了使用我们的APC非依赖菌株来分析APC在细胞周期进程中的功能及其工作机制的策略。

DESCRIPTION (provided by applicant): Progress through the cell cycle is controlled by the periodic synthesis and degradation of a large number of regulatory proteins. Cell cycle regulated degradation of proteins is accomplished by modifying proteins with ubiquitin, which then targets those proteins to the proteosome. Addition of ubiquitin is carried out by a class of enzymes called ubiquitin ligases. One of the most important ubiquitin ligases regulating cell cycle progression is called the anaphase promoting complex (APC). While many ubiquitin ligases are monomeric enzymes, the APC is a complex of 13 subunits, almost all of which are conserved in all eukaryotes. In addition to this core, catalytic complex, the APC associates with either of two specificity factors, called Cdc20 and Cdhl. These proteins are thought to mediate the APC's interaction with its substrates. Loss of any essential APC subunit results in a cell-cycle arrest in metaphase. Remarkably, any of the normally essential APC genes can be deleted if two important APC targets are deleted/inhibited: securin (Pds l) and the B-type cyclin/CDK complex. In addition to providing valuable information about the function of the APC in cell division, this work has also generated a novel tool for studying the enzymology and regulation of the APC. In this strain, we are able to modify the APC complex in ways that would be lethal in a wild type background. This proposal outlines strategies for using our APC-independent strains to analyze the function of the APC in cell cycle progression and the mechanisms by which it works.