The cdk2 kinase is required for the G1-to-S transition in mammalian cells.
The cdk2 kinase is required for the G1-to-S transition in mammalian cells.
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发表时间：
1993-06
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影响因子：
8
通讯作者：
L. Tsai;E. Lees;B. Faha;E. Harlow;K. Riabowol
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作者：
L. Tsai;E. Lees;B. Faha;E. Harlow;K. Riabowol
在裂殖酵母和芽殖酵母的细胞周期中，p34cdc2/CDC28 激酶是 G1 至 S 和 G2 至 M 相转变所必需的。在脊椎动物中，同源 p34cdc2 激酶是 G2 到 M 相转变所必需的，但对于 DNA 合成似乎是可有可无的。我们使用血清刺激的静止人类成纤维细胞研究了相关激酶 p33cdk2 的功能。虽然 p33cdk2 蛋白在整个细胞周期中以恒定水平表达，但 p33cdk2 激酶活性在 DNA 合成开始前几小时首次检测到。显微注射抗 p33cdk2 抗体可阻止细胞进入 S 期。这些抗体与 cdk2 蛋白的预吸附消除了它们的阻断作用，表明这些抗体引起的 G1 停滞是 cdk2 特异性的。这些结果表明 p33cdk2 是哺乳动物细胞 G1 至 S 相转变所必需的。我们还显示证据表明，进入 S 期可能需要周期蛋白 E/p33cdk2 复合物，因为周期蛋白 E 相关激酶活性的时间与 p33cdk2 的时间一致，并且任一组分的预清除消除了从 G1 晚期收获的裂解物中存在的大部分组蛋白 H1 激酶活性。
In the cell cycle of fission and budding yeast, the p34cdc2/CDC28 kinase is required for both the G1-to-S and G2-to-M phase transitions. In vertebrates, the homologous p34cdc2 kinase is required for G2-to-M phase transitions but appears to be dispensable for DNA synthesis. We have investigated the function of a related kinase, p33cdk2, using serum-stimulated quiescent human fibroblasts. While the p33cdk2 protein was expressed at constant levels throughout the cell cycle, p33cdk2 kinase activity was first detected a few hours prior to the onset of DNA synthesis. Microinjection of anti-p33cdk2 antibodies blocked cells from entering S phase. Pre-adsorption of these antibodies with cdk2 protein abrogated their blocking effect suggesting that the G1 arrest caused by these antibodies is cdk2-specific. These results indicate that p33cdk2 is required for the G1-to-S phase transition in mammalian cells. We also show evidence to suggest that the cyclin E/p33cdk2 complex is likely to be required for entry into S phase since the timing of the cyclin E-associated kinase activity was coincident with that of p33cdk2 and preclearing of either component abolished the majority of the histone H1 kinase activity present in the lysates harvested from the late G1.