Biochemistry of Cell Cycle Regulation

描述（由申请人提供）：通过细胞周期的进展是 受细胞周期蛋白依赖的 蛋白激酶（CDKs）。所有的细胞周期cdk，如人Cdc 2，Cdk 2， 和Cdk 4，以及酵母Cdc 2Sp，需要在一个位点上激活磷酸化 相当于人Cdk 2中的Thr-160。这种磷酸化是通过 CAK，Cdk激活激酶。在大多数物种中，CAK由催化剂组成。 亚基Cdk 7、调节亚基细胞周期蛋白H和组装因子MAT 1。 所有这三种蛋白质也是一般转录的亚基 因子TFIIH。然而，在酵母中，CAK由单一多肽Cakip组成。 由CAK进行的磷酸化被2C型去除， 磷酸酶（PP 2C）。这些研究旨在加深我们对 在酵母和脊椎动物中激活CDK的磷酸化。的 本项目的具体目标是：1）使用“模拟敏感”（asi）， Cakip和CDK 7的“类似物特异性”（as 2）形式，以研究CAK功能， 酵母和人类的底物。2）描述PP 2C的调节特性 通过N-末端豆蔻酰化的活性，并鉴定额外的PP 2C 酵母中的底物。3）为了检验CDK中的差异 芽殖酵母和大多数其他物种的激活途径是由 在这些生物体中，分别是封闭的和开放的有丝分裂。（4）调查原因 CDK已被设计为需要激活磷酸化，并确定 在细胞周期蛋白表达后哺乳动物CDK不去磷酸化的后果 降解

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.