Biochemistry of Cell Cycle Regulation

描述(申请人提供)：细胞周期进程为 受细胞周期蛋白依赖的顺序激活和失活的调节 蛋白激酶(CDKs)。所有的细胞周期CDK，如人的CDC2，CDK2， 和cdk4，以及酵母cdc2Sp，需要在一个位点上激活磷酸化 相当于人类CDK2中的Thr-160。这种磷酸化是通过以下方式进行的 CAK，CDK激活的激酶。在大多数物种中，CAK由一个催化剂组成 亚基CDK7、调节亚基Cyclin H和组装因子MAT 1。 这三种蛋白质也都是一般转录的亚基。 TFIIH因素。然而，在酵母中，CAK由单一的多肽组成，即Cakip。 由CAK进行的磷酸化被2C型去除 磷酸酶(PP2Cs)。这些研究的目的是加深我们对 在酵母和脊椎动物中激活CDKs的磷酸化。这个 该项目的具体目标是：1)使用模拟敏感(ASI)和 CAKIP和CDK7的“特定模拟”(AS2)形式，以研究CAK功能和 酵母菌和人类的底物。2)表征PP2C的调控 N-末端肉豆蔻酰化的活性和鉴定额外的PP2C 酵母中的底物。3)检验CDK差异的假设 萌芽酵母和大多数其他物种的激活途径是由 在这些有机体中，分别有闭合的有丝分裂和开放的有丝分裂。4)调查原因 CDK被设计成需要激活磷酸化并确定 哺乳动物CDK在周期后不去磷酸化的后果 退化。

DESCRIPTION (provided by applicant): Progression through the cell cycle is regulated by the sequential activation and inactivation of cyclin-dependent protein kinase (cdks). All of the cell cycle cdks, such as human Cdc2, Cdk2, and Cdk4, and yeast Cdc2Sp, require an activating phosphorylation on a site equivalent to Thr-160 in human Cdk2. This phosphorylation is carried out by CAK, the Cdk-Activating Kinase. In most species, CAK consists of a catalytic subunit, Cdk7, a regulatory subunit, cyclin H, and an assembly factor, MAT 1. All three of these proteins are also subunits of the general transcription factor TFIIH. In yeast, however, CAK consists of a single polypeptide, Cakip. The phosphorylation that is carried out by CAK is removed by Type 2C phosphatases (PP2Cs). These studies are aimed at furthering our understanding of activating phosphorylations of cdks, both in yeast and in vertebrates. The Specific Aims of this project are: 1) To use "analog-sensitive" (asi) and "analog-specific" (as2) forms of Cakip and CDK7 to study CAK functions and substrates in yeast and humans. 2)To characterize the regulation of PP2C activity by N-terminal myristoylation and to identify additional PP2C substrates in yeast. 3)To test the hypothesis that the differences in the CDK activation pathways of budding yeast and of most other species result from the closed vs. open mitoses in these organisms, respectively. 4)To investigate why CDKs have been designed to require activating phosphorylations and to determine the consequences of not dephosphorylating a mammalian CDK following cyclin degradation.