CDC2-LIKE KINASES IN NORMAL AND MALIGNANT CELLS

最近的研究表明，哺乳动物中存在一个蛋白质家族 蛋白激酶与酵母细胞周期的结构和功能相关 调节激酶CDC-2。CDC2家族的两个成员，CDK1和CDK2， 已经在哺乳动物细胞中被发现。CDK1激酶调节细胞周期 从G2到M的进程，以及CDK2被提出来调节 从G1期进入S期。我们已经克隆并在结构上 鉴定了cdc2激酶家族的另一个成员，cdk 5，具有 氨基酸序列与小鼠cdk 1的同源性为58%，与人的同源性为60% CDK2。与cdk 1或cdk 2相反，cdk 5高表达。 终末分化神经元中的水平。此外，许多培养的细胞 细胞系表达高水平的cdk5、cdk1和cdk2蛋白。 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 Cdk5特异性抗肽抗血清，可特异性 免疫沉淀法从哺乳动物细胞提取液中提取cdk-5激酶，并结合 在Western blotting研究中具体到cdk 5。使用这种抗血清， 我们已经证实，培养的人类肿瘤细胞以酶的方式表达 活性CDK5激酶。此外，CDK 5和细胞周期蛋白D是一种调节因子 激酶活性所需的因子，已在大肠杆菌中共表达。 产酸酶的酶学性质研究 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.