Anaphase Promoting Complex-mediated Proteolysis

有丝分裂进展和退出过程中的一个关键事件是泛素依赖性的降解 周期蛋白和其他关键蛋白由后期促进复合体(ARC；也称为环体)。 底物含有降解模体，如销毁盒子和肯箱，这是 它们的泛素化以及它们与ARC激活剂CDC20和CDH1的结合。这两个图案都是必需的 用于有效降解，但其中任何一种单独都足以与CDHLP结合。我们提出了一条途径 用于组装其中不含APC的CDHLP首先与衬底结合的APC-CDHIP-衬底复合体。 CDH1P与底物破坏盒的接合刺激了CDH1P与ARC的结合， 推测是通过CDhlp的构象变化。 目前的研究旨在加深我们对发芽过程中APC介导的蛋白水解酶的理解 酵母。特别是，我们希望确定新的ARC衬底，以了解如何 APC-CDH1P/CdC20P-底物络合物的组装和拆解，以及为了了解 主轴组件检查点在以下情况下使用KEN盒来关闭APC介导的蛋白质分解 染色体没有正确地附着在有丝分裂纺锤体上。 为实现这些目标，我提出以下具体目标： 1)寻找新的ARC底物。 2)评估APC-CDHIP-底物组装途径的一般性。 3)确定D-Box参与如何刺激CDh1p与ARC结合： 4)确定保守的cdhlp基序和磷酸化在apc-cdh1p底物中的作用。 集合。 5)确定APC-Cdh1p-底物复合体的解离是否是一个活性过程。 6)确定主轴组件检查点中MadSp Ken Box的功能。 关键蛋白质的降解是细胞分裂所必需的。因此，理解这种退化是 对于理解正常的细胞增殖以及这一过程在疾病状态下如何出错非常重要， 尤其是癌症。

A key event in the progression through and exit from mitosis is the ubiquitin-dependent degradation of cyclins and other key proteins by the Anaphase Promoting Complex (ARC; also called the cyclosome).ARC substrates contain degradation motifs such as the Destruction Box and the KEN Box that are required for their ubiquitination and for their binding to the ARC activators, Cdc20 and Cdh1. Both motifs are required for efficient degradation, but either one alone suffices for binding to Cdhlp. We have proposed a pathway for the assembly of the APC-Cdhip-substrate complex in which APC-free Cdhlp first binds a substrate. Engagement of the substrate Destruction Box by Cdh1p stimulates the binding of Cdh1p to the ARC, presumably via a conformation change in Cdhlp. The current studies are aimed at furthering our understanding of APC-mediated protedlysis in budding yeast. In particular, we wish to identify novel ARC substrates, to understand how APC-Cdh1p/Cdc20p-substrate complexes are assembled and disassembled, and to understand how the spindle assembly checkpoint makes use of a KEN box to turn off APC-mediated proteolysis when chromosomes are not properly attached to the mitotic spindle. To achieve these goals, I propose the following Specific Aims: 1) To Identify Novel ARC Substrates. 2) To Assess the Generality of the APC-Cdhip-Substrate Assembly Pathway. 3) To Determine How D-Box Engagement Stimulates Cdh1p Binding to the ARC: 4) To Determine the Roles of Conserved Cdhlp Motifs and of Phosphcrylation in APC-Cdh1p-Substrate Assembly. 5) To Determine Whether Disassembly of the APC-Cdh1p-Substrate Complex is an Active Process. 6) To Determine the Function of the MadSp KEN Box in the Spindle Assembly Checkpoint. Degradation of key proteins is essential for cell division. Understanding this degradation is thus important for understanding normal cell proliferation, and how this process goes awry in disease states, particularly cancers.