Phosphorylation of DNA topoisomerase II in a human tumor cell line.
The phosphorylation of the nuclear enzyme DNA topoisomerase II was characterized from HeLa human cervical carcinoma cells labeled with 32Pi. Analysis of topoisomerase II immunoprecipitates from 32P-labeled HeLa cells indicated that phosphorylation of the enzyme occurred at serine residues. Incorporation of 32P into topoisomerase II was not due to other types of phosphomodifications such as poly(ADP-ribosylation) or covalent interactions of the enzyme with nucleic acids. The stability of topoisomerase II protein and topoisomerase II phosphorylation was also investigated in HeLa cells. Topoisomerase II protein was relatively stable, having a half-life of approximately 27 h. Phosphorylation of HeLa topoisomerase II was also remarkably stable with a T1/2 of 17 h.
Kroll
D J
DJ
Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville 32610-0267.
Rowe
T C
TC
D000596:Amino Acids / Q000032:analysis; D004250:DNA Topoisomerases, Type II / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D006367:HeLa Cells; D006801:Humans; D010710:Phosphates / Q000378:metabolism; D010766:Phosphorylation; D011233:Precipitin Tests; D014407:Tumor Cells, Cultured
D000596:Amino Acids; D010710:Phosphates; D004250:DNA Topoisomerases, Type II