BIOCHEMISTRY OF CELL CYCLE REGULATION

描述：通过细胞周期的进展是由 一系列细胞周期蛋白依赖的 蛋白激酶（CDKs）。 许多cdk，如p34 cdc 2和cdc 4，都需要一个 激活相当于人p34 cdc 2中Thr-161位点的磷酸化。 这种磷酸化是由CAK，Cdk激活激酶进行的。 所罗门和其他人纯化了脊椎动物的CAK，发现它含有 至少两种蛋白质，称为p40 MO 15（或cdk 7）的催化亚基，和 调节亚基，细胞周期蛋白H。这两种蛋白质也是一般蛋白质的亚基。 转录因子TFIIH。 他最近从芽殖酵母中提纯了CAK， 发现它由一个单一的亚基（Cak 1 p）组成， 蛋白激酶基序，与先前鉴定的 CAKs。 由于p40 MO 15的转录功能在酵母中由 Kin 28 p，将Cak 1 p鉴定为生理酵母CAK，表明 脊椎动物中可能存在另外一种CAK，一种更像Cak 1 p， p40MO 15。 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是如此。 该项目的具体目标是： 1)为了确定Cak 1 p底物的范围，它是如何调节的，以及 它的三维结构。 2)为了表征最终产品 抑制Cak 1 p并确定其生理作用。 3)到 确定p40 MO 15是否是脊椎动物中的生理CAK，以筛选 其他真菌的Cak 1 p样CAK的证据，寻找额外的 脊椎动物CAK，类似于酵母Cak 1 p，并评估其功能 重要性 4)为了鉴定和研究对抗Cak 1 p的磷酸酶， 使Cdc 28 p的Thr-169去磷酸化。

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.