Chromatin-bound histone 1 kinase activity in synchronized HeLa S3 cells.
The chromatin-bound H1 kinase activity of HeLa S3 cells that had been synchronized with 2.7 mM thymidine for 24 h has been followed during their progression into mitosis. They were arrested at this stage of the cell cycle by adding 0.13 microM nocodazole 8 h after the removal of thymidine. The kinase was partially purified by extracting chromatin proteins with 0.4 M NaCl and fractionation with ammonium sulfate (17.5-35%), a procedure in which a significant amount of in vivo histone 1 phosphorylating activity was retained. H1 kinase activity increased as the cells entered mitosis, rising to a maximum level sevenfold higher than interphase as the mitotic index reached about 50%. A rapid decrease in activity followed this maximum approximately 2 h after cells started to accumulate in mitosis. At this time, the mitotic index was still increasing, although at a lower rate than during the increase of the kinase activity. Other protein kinase activities measured by using core histones, casein, and protamine as substrates remained fairly constant at a comparatively low level. HeLa H1 kinase activity was further distinguished from several known protein kinase activities by the lack of stimulation or inhibition with known modulators of protein phosphorylating activities.
Müller
K
K
Institute of Cell and Tumor Biology, German Cancer Research Center, Heidelberg.
Little
M
M
D002118:Calcium / Q000494:pharmacology; D002843:Chromatin / Q000201:enzymology*; D000242:Cyclic AMP / Q000494:pharmacology; D006367:HeLa Cells; D006493:Heparin / Q000494:pharmacology; D006657:Histones / Q000378:metabolism; D006801:Humans; D008938:Mitosis; D008940:Mitotic Index; D010743:Phospholipids / Q000494:pharmacology; D006656:Protamine Kinase / Q000302:isolation & purification / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D002843:Chromatin; D006657:Histones; D010743:Phospholipids; D006493:Heparin; D000242:Cyclic AMP; D011494:Protein Kinases; D006656:Protamine Kinase; D002118:Calcium