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首页> 外文期刊>Molecular and Cellular Biology >Cyclin-binding motifs are essential for the function of p21CIP1.
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Cyclin-binding motifs are essential for the function of p21CIP1.

机译:细胞周期蛋白结合基序对于p21CIP1的功能至关重要。

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The cyclin-dependent kinase (Cdk) inhibitor p21 is induced by the tumor suppressor p53 and is required for the G1-S block in cells with DNA damage. We report that there are two copies of a cyclin-binding motif in p21, Cy1 and Cy2, which interact with the cyclins independently of Cdk2. The cyclin-binding motifs of p21 are required for optimum inhibition of cyclin-Cdk kinases in vitro and for growth suppression in vivo. Peptides containing only the Cy1 or Cy2 motif partially inhibit cyclin-Cdk kinase activity in vitro and DNA replication in Xenopus egg extracts. A monoclonal antibody which recognizes the Cy1 site of p21 specifically disrupts the association of p21 with cyclin E-Cdk2 and with cyclin D1-Cdk4 in cell extracts. Taken together, these observations suggest that the cyclin-binding motif of p21 is important for kinase inhibition and for formation of p21-cyclin-Cdk complexes in the cell. Finally, we show that the cyclin-Cdk complex is partially active if associated with only the cyclin-binding motif of p21, providing an explanation for how p21 is found associated with active cyclin-Cdk complexes in vivo. The Cy sequences may be general motifs used by Cdk inhibitors or substrates to interact with the cyclin in a cyclin-Cdk complex.
机译:细胞周期蛋白依赖性激酶(Cdk)抑制剂p21由肿瘤抑制因子p53诱导,是DNA损伤细胞中G1-S阻断所必需的。我们报告说,在p21中,细胞周期蛋白结合基序有两个拷贝,Cy1和Cy2,它们与细胞周期蛋白独立于Cdk2相互作用。 p21的细胞周期蛋白结合基序是体外抑制细胞周期蛋白Cdk激酶和体内抑制生长所需的。仅包含Cy1或Cy2基序的肽在体外和非洲爪蟾卵提取物中的DNA复制中均部分抑制cyclin-Cdk激酶活性。识别p21 Cy1位点的单克隆抗体可特异性破坏细胞提取物中p21与细胞周期蛋白E-Cdk2和细胞周期蛋白D1-Cdk4的结合。综上所述,这些观察结果表明p21的细胞周期蛋白结合基序对于激酶抑制和细胞中p21-细胞周期蛋白-Cdk复合物的形成很重要。最后,我们显示,如果仅与p21的细胞周期蛋白结合基序相关,则细胞周期蛋白-Cdk复合物是部分活性的,从而提供了如何在体内发现p21与活性细胞周期蛋白-Cdk复合物相关的解释。 Cy序列可以是Cdk抑制剂或底物用来与细胞周期蛋白-Cdk复合物中的细胞周期蛋白相互作用的一般基序。

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