NOVEL CDK6-ASSOCIATED PROTEIN

细胞周期进程是一个严格调控的事件， 这是癌症的标志。 真核细胞周期是 由细胞周期蛋白依赖性激酶的时间关联控制 (cdk)与细胞周期蛋白伴侣，导致这些激活 复合物和随后的关键底物的磷酸化。 哺乳动物的D型细胞周期蛋白和它们的cdk配偶体cdk 4和cdk 6， G1期进展的重要调节因子;关于如何 然而，这些CDK/细胞周期蛋白复合物受到调节。这项建议 描述了一种 在cdk 6免疫沉淀物中发现的新的约28 kDa蛋白（p28） 含有分离自早期人T细胞的D型细胞周期蛋白， G1期令人好奇的是，p28与产生的抗 p27 KIP 1是最近发现的cdk抑制剂，但与 p27KIP1。这些发现提出了一种有趣的可能性，即p28 代表一种新的cdk抑制剂，并且它与cdk 6/ 细胞周期蛋白D复合物对G1期有重要的调控作用 控制知道p28的cDNA序列将允许其表达， 与各种CDK/细胞周期蛋白复合物的结合作为细胞周期蛋白的功能， 细胞周期分析。p28影响激酶的可能性 cdk 6/细胞周期蛋白D复合物或其它cdk/细胞周期蛋白复合物的活性 将被调查。p28所需的p28上的最小结构域 与CDK/细胞周期蛋白复合物的结合和对CDK/细胞周期蛋白复合物的活性将是 映射。最后，通过瞬时转染过表达p28， 通过显微注射抗p28蛋白的功能性失活 抗体和反义DNA将试图研究一个在 p28的体内作用。

Cell cycle progression is a tightly regulated event, the deregulation of which is a hallmark of cancer. Eukaryotic cell cycles are controlled by the temporal association of a cyclin dependent kinase (cdk) with a cyclin partner, leading to the activation of these complexes and the subsequent phosphorylation of critical substrates. The mammalian D-type cyclins and their cdk partners, cdk4 and cdk6, are important regulators of G1 phase progression; little is known about how these cdk/cyclin complexes are regulated, however. This proposal describes the molecular cloning and biochemical characterization of a novel approximate 28 kDa protein (p28) found in cdk6 immunoprecipitates containing D-type cyclins isolated from primary human T- cells in early G1 phase. Curiously, p28 immunoreacts with antibodies generated against p27KIP1, a recently identified cdk inhibitor, yet is distinct from p27KIP1. These findings raise the intriguing possibility that p28 represents a novel cdk inhibitor and that its association with cdk6/ cyclin D complexes has an important regulatory function for G1 phase control. Knowing the cDNA sequence of p28 will allow its expression and association with various cdk/ cyclin complexes as a function of the cell cycle to be analyzed. The possibility that p28 affects the kinase activity of cdk6/ cyclin D complexes or other cdk/ cyclin complexes will be investigated. The minimal domains on p28 required for p28 association with and activity towards cdk/ cyclin complexes will be mapped. Lastly, overexpression of p28 by transient transfection and functional inactivation of the protein by microinjection of anti-p28 antibodies and antisense DNA will be attempted to investigate an in vivo role for p28.