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，然后将这些蛋白质靶向蛋白体来完成的。泛素的添加是由一类称为泛素连接酶的酶进行的。调节细胞周期进程的最重要的遍在蛋白连接酶之一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13个亚基的复合物，几乎所有亚基在所有真核生物中都是保守的。除了这种核心催化复合物之外，APC还与两种特异性因子中的任何一种相关联，称为Cdc 20和Cdhl。这些蛋白质被认为介导APC与其底物的相互作用。任何必需的APC亚基的丢失都会导致细胞周期停滞在中期。值得注意的是，如果缺失/抑制两个重要的APC靶：securin（Pds 1）和B型细胞周期蛋白/CDK复合物，则可以缺失任何正常必需的APC基因。除了提供关于APC在细胞分裂中的功能的有价值的信息之外，这项工作还产生了用于研究APC的酶学和调节的新工具。在该菌株中，我们能够以在野生型背景下将是致命的方式修饰APC复合物。该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.