BIOCHEMISTRY OF CELL CYCLE REGULATION

描述：细胞周期中的进程由 一系列细胞周期蛋白依赖蛋白的顺序激活和失活 蛋白激酶(CDKs)。许多CDK，如p34cdc2和cdc4，都需要 激活人p34cdc2中与Thr-161等同的位点的磷酸化。 这种磷酸化是由CDK激活的激酶CAK完成的。 所罗门和其他人提纯了脊椎动物CAK，并发现它含有 至少两个蛋白质，一个称为p40MO15(或CDK7)的催化亚基，以及一个 调节亚基，细胞周期蛋白H。这两种蛋白也是普通蛋白的亚基。 转录因子TFIIH。他最近从萌芽中的酵母中提纯了CAK， 并发现它由单个亚基(Cak1p)组成，具有不寻常的 蛋白激酶基序与先前鉴定的仅有较远的相似性 卡克斯。由于p40MO15的转录功能在酵母中是通过 Kin28p，鉴定Cak1p为生理酵母菌CAK 可能有另外一种脊椎动物CAK，比Cak1p更像Cak1p P40MO15。这些研究旨在加深我们对CAK的理解， 在酵母和脊椎动物中都有。该项目的具体目标是： 1)确定Cak1p底物的范围，如何调节它，以及 它的三维结构。2)确定最终产品的特征 抑制Cak1p并确定其生理作用。3)至 确定p40MO15是否是脊椎动物中的生理性CAK，以进行筛选 其他真菌寻找类似Cak1p的CAK的证据，以寻找另一种 脊椎动物CAK，类似于酵母Cak1p，并对其功能进行了评估 重要性。4)鉴定和研究与Cak1p相关的磷酸酶 对Cdc28P的Thr-169进行脱磷。

DESCRIPTION: Progression through the cell cycle is regulated by the sequential activation and inactivation of a number of cyclin-dependent protein kinase (cdks). Many cdks, such as p34cdc2, and cdc4 require an activating phosphorylation on a site equivalent to Thr-161 in human p34cdc2. This phosphorylation is carried out by CAK, the Cdk-Activating Kinase. Solomon and others purified vertebrate CAK and found that it contained at least two proteins, a catalytic subunit termed p40MO15 (or cdk7), and a regulatory subunit, cyclin H. Both proteins are also subunits of the general transcriptio factor TFIIH. He recently purified CAK from the budding yeast, and found that it was composed of a single subunit (Cak1p) with unusual protein kinase motifs and only distant similarity to previously identified CAKs. Since the transcription function of p40MO15 is performed in yeast by Kin28p, the identification of Cak1p as the physiological yeast CAK suggested that there might be an additional vertebrate CAK, one more like Cak1p than p40MO15. These studies are aimed at furthering our understanding of CAK, both in yeast and in vertebrates. The Specific Aims of this project are: 1) To determine the range of Cak1p's substrates, how it is regulated, and its three-dimensional structure. 2) To characterize the end-product inhibition of Cak1p and to determine its physiological role. 3) To determine whether p40MO15 is a physiological CAK in vertebrates, to screen other fungi for evidence of a Cak1p-like CAK, to search for an additional vertebrate CAK, similar to yeast Cak1p, and to assess its functional importance. 4) To identify and study the phosphatase that counters Cak1p by dephosphorylating Thr-169 of Cdc28p.