Devoto S H, Mudryj M, Pines J, Hunter T, Nevins J R
Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina 27710.
Cell. 1992 Jan 10;68(1):167-76. doi: 10.1016/0092-8674(92)90215-x.
The E2F transcription factor has been found in association with the cyclin A protein, and this complex accumulates during the S phase of the cell cycle, suggesting that E2F may play a role in cell cycle control. In independent studies, cyclin A has been shown to be associated with two other proteins, the Rb-related p107 protein and the cdc2-related p33 cdk2 protein kinase. Through an analysis of the E2F-cyclin A complex, we now find that both the p107 protein and the cdc2-related p33cdk2 kinase are components of the previously described complex. Moreover, the complex possesses H1 kinase activity. These results thus define a cyclin A-cdk2 kinase complex that possesses sequence-specific DNA binding activity. This suggests that the cdk2 kinase may phosphorylate other DNA-bound substrates, and that one role of the E2F factor may be to localize this protein kinase to the DNA.
已发现E2F转录因子与细胞周期蛋白A相关，并且这种复合物在细胞周期的S期积累，这表明E2F可能在细胞周期调控中发挥作用。在独立研究中，细胞周期蛋白A已被证明与另外两种蛋白质相关，即与Rb相关的p107蛋白和与cdc2相关的p33 cdk2蛋白激酶。通过对E2F - 细胞周期蛋白A复合物的分析，我们现在发现p107蛋白和与cdc2相关的p33cdk2激酶都是先前描述的复合物的组成成分。此外，该复合物具有H1激酶活性。因此，这些结果确定了一种具有序列特异性DNA结合活性的细胞周期蛋白A - cdk2激酶复合物。这表明cdk2激酶可能磷酸化其他与DNA结合的底物，并且E2F因子的一个作用可能是将这种蛋白激酶定位到DNA上。
