CDC2-LIKE KINASES IN NORMAL AND MALIGNANT CELLS

最近的研究表明，存在一个哺乳动物蛋白质家族， 结构和功能上与酵母细胞周期相关的激酶 调节激酶cdc-2。 cdc 2家族的两个成员cdk 1和cdk 2， 已经在哺乳动物细胞中被发现。 cdk 1激酶调节 从G2到M的进展，cdk 2已经被提出来调节细胞增殖。 从G1期进入S期。 我们克隆了 其特征在于CDC 2激酶家族的另外一个成员CDK 5， 与小鼠CDK 1的氨基酸序列同源性为58%，与人CDK 1的氨基酸序列同源性为60% cdk2. 与cdk 1或cdk 2相反，cdk 5在高水平表达。 终末分化神经元的水平。此外，许多培养的细胞 细胞系表达高水平的cdk 5 mRNA以及cdk 1和cdk 2激酶。 我们正在探索cdk 5在细胞周期调控中的作用， 有丝分裂活性细胞和人类肿瘤。我们已经生成了一个 特异性针对CDK 5的抗肽抗血清， 免疫沉淀来自哺乳动物细胞提取物CDK 5激酶，并结合 在Western印迹研究中特异性结合CDK 5。 使用这种抗血清， 我们已经确定，培养的人类肿瘤细胞表达酶促 活性CDK 5激酶 此外，cdk 5和细胞周期蛋白D， 激酶活性所需的因子，已在E.杆菌 表征在大肠杆菌中产生的激酶的酶性质。 细菌目前正在进行中。

Recent studies have shown that there exists a family of mammalian protein kinases structurally and functionally related to the yeast cell cycle regulatory kinase cdc-2. Two members of the cdc2 family, cdk1 and cdk2, have been identified in mammalian cells. Cdk1 kinase regulates the progression from G2 to M, and cdk2 has been proposed to regulate the progression from G1 to S phase. We have cloned and structurally characterized an additional member of the cdc2 kinase family, cdk 5, with 58% amino acid sequence identity to mouse cdk 1 and 60% identity to human cdk2. In contrast to either cdk 1 or cdk2, cdk 5 is expressed at high levels in terminally differentiated neurons. Moreover, many cultured cell lines express high levels of cdk 5 mRNA as well as cdk 1 and cdk2 kinase. We are exploring the role of cdk 5 in cell cycle regulation of mitotically active cells and human tumors. We have generated an antipeptide antiserum specific for cdk 5, which can specifically immunoprecipitate cdk 5 kinase from mammalian cell extracts, and binds specifically to cdk 5 in Western blotting studies. Using this antiserum, we have established that cultured human tumor cells express enzymatically active cdk 5 kinase. In addition, cdk 5 and cyclin D, a regulatory factor needed for kinase activity, have been co-expressed in E. coli. Characterization of the enzymatic properties of the kinase produced in bacteria is currently underway.