Structure and function of the APC

描述（由申请人提供）：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到蛋白质体上。泛素的添加是由一类称为泛素连接酶的酶进行的。调控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物（APC）。虽然许多泛素连接酶是单体酶，但APC是一个由13个亚基组成的复合物，几乎所有这些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物外，APC还与两种特异性因子Cdc20和Cdhl结合。这些蛋白被认为介导APC与其底物的相互作用。任何重要APC亚基的缺失都会导致细胞周期中期停滞。值得注意的是，如果两个重要的APC靶点：安全蛋白（Pds - 1）和b型细胞周期蛋白/CDK复合物被删除/抑制，任何正常必需的APC基因都可以被删除。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种新的工具。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。本提案概述了使用我们的APC独立菌株来分析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.