Marshak D R, Russo G L
Cold Spring Harbor Laboratory, New York.
Cell Mol Biol Res. 1994;40(5-6):513-7.
Protein kinase CKII is a prevalent serine/threonine protein kinase whose structure is highly conserved among eukaryotic organisms. Its involvement in the eukaryotic cell division cycle has been implicated by genetic experiments in yeast, antisense DNA, and inhibitory antibody experiments in mammalian cells, changes in activity during growth stimulation experiments, and protection of cells from radiation damage to replicating DNA. In addition, the cdc2 protein kinase, which is central to cell division cycle control, serves as a substrate for CKII specifically during the G1 phase of human cells. In this report, extracts of HeLa cells were prepared using neutral, aqueous buffers at low ionic strength. The cells were enriched for specific stages of the cell division cycle by treatment with drugs or by centrifugal elutriation. The results indicate that CKII activity in these extracts is highest during the G1 phase, and there appears to be a reduction in soluble CKII activity during the S phase. These data are consistent with the hypothesis that high CKII is necessary for a normal G1 phase but that progression through the S phase requires inhibition of CKII.
蛋白激酶CKII是一种普遍存在的丝氨酸/苏氨酸蛋白激酶，其结构在真核生物中高度保守。酵母中的基因实验、哺乳动物细胞中的反义DNA和抑制性抗体实验、生长刺激实验期间活性的变化以及细胞免受复制DNA辐射损伤的保护作用都表明它参与了真核细胞分裂周期。此外，对细胞分裂周期控制至关重要的cdc2蛋白激酶，在人类细胞的G1期特别作为CKII的底物。在本报告中，使用低离子强度的中性水性缓冲液制备了HeLa细胞提取物。通过药物处理或离心淘洗使细胞富集细胞分裂周期的特定阶段。结果表明，这些提取物中的CKII活性在G1期最高，而在S期可溶性CKII活性似乎有所降低。这些数据与以下假设一致，即高CKII水平对于正常的G1期是必要的，但进入S期需要抑制CKII。
