CDC25M2 ACTIVATION OF CYCLIN-DEPENDENT KINASES BY DEPHOSPHORYLATION OF THREONINE-14 AND TYROSINE-15
CDC25M2 ACTIVATION OF CYCLIN-DEPENDENT KINASES BY DEPHOSPHORYLATION OF THREONINE-14 AND TYROSINE-15
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DOI：
10.1073/pnas.90.8.3521
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发表时间：
1993-04-15
影响因子：
11.1
通讯作者：
HUNTER, T
中科院分区：
文献类型：
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作者：
SEBASTIAN, B;KAKIZUKA, A;HUNTER, T
最近的证据表明，人细胞周期蛋白依赖性激酶2(CDK2)是细胞周期通过S时相的重要调节因子。已知CDK2与至少两个不同的人周期蛋白E和A形成复合体。这两个复合体的激活峰分别出现在G1和S时相。脊椎动物CDC2/Cyclin B1复合体是有丝分裂开始的重要调节因子，并被Thr-14和Tyr-15上CDC2的磷酸化抑制。在体外，CDC2/Cyclin B1可以通过处理CDC25磷酸酶家族的成员来激活。我们发现，像CDC2一样，CDK2也在Thr-14和Tyr-15上被磷酸化，并且用细菌表达的CDC25M2(人CDC25B的小鼠同源物)处理Cyclin A或Cyclin E免疫沉淀物时，这些免疫复合体的组蛋白H1激酶活性增加了5-10倍。胰酶多肽图谱显示，细胞周期蛋白A和细胞周期蛋白B1免疫复合物的CDc25M2处理分别导致CDK2和CDC2上Thr-14和Tyr-15的特异性去磷酸化。因此，我们已经证实CDC25家族成员由一类双特异性磷酸酶组成。此外，我们的数据表明，CDKs在Thr-14和Tyr-15上的磷酸化和去磷酸化不仅可能调节细胞周期的G2/M转变，还可能调节细胞周期的其他转变，CDC25家族成员可能调节不同的细胞周期检查点。
Recent evidence has suggested that human cyclin-dependent kinase 2 (CDK2) is an essential regulator of cell cycle progression through S phase. CDK2 is known to complex with at least two distinct human cyclins, E and A. The kinase activity of these complexes peaks in G1 and S phase, respectively. The vertebrate CDC2/cyclin B1 complex is an essential regulator of the onset of mitosis and is inhibited by phosphorylation of CDC2 on Thr-14 and Tyr-15. In vitro, CDC2/cyclin B1 is activated by treatment with the members of the Cdc25 family of phosphatases. We found that, like CDC2, CDK2 is also phosphorylated on Thr-14 and Tyr-15 and that treatment of cyclin A or cyclin E immunoprecipitates with bacterially expressed Cdc25M2 (the mouse homolog of human CDC25B) increased the histone H1 kinase activity of these immune complexes 5- to 10-fold. Tryptic peptide mapping demonstrated that Cdc25M2 treatment of cyclin A or cyclin B1 immune complexes resulted in the specific dephosphorylation of Thr-14 and Tyr-15 on CDK2 or CDC2, respectively. Thus, we have confirmed that Cdc25 family members comprise a class of dual-specificity phosphatases. Furthermore, our data suggest that the phosphorylation and dephosphorylation of CDKs on Thr-14 and Tyr-15 may regulate not only the G2/M transition but also other transitions in the cell cycle and that individual cdc25 family members may regulate distinct cell cycle checkpoints.