The regulation of thymidine kinase in HL-60 human promyeloleukemia cells.
It has been well established that the regulation of thymidine kinase (TK) expression is highly growth-dependent. In this report, we present evidence that TK expression in undifferentiated HL-60 cells is not stringently controlled in a growth-dependent manner, except for a very moderate activation of TK in response to growth stimulation. Moreover, we have demonstrated for the first time that TK becomes phosphorylated, and the fluctuation of TK activity in these cells is related to the extent of phosphorylation of seryl residues of the TK polypeptide. This is further reinforced by the observation that the presence of Ser/Thr phosphatases inhibitor in the crude extract increases TK activity. Our data suggest that post-translational modification by phosphorylation is implicated in TK regulation in HL-60 cells.
Chang
Z F
ZF
Department of Biochemistry, Chang Gung Medical College, Tao-Yuan, Taiwan, Republic of China.
Huang
D Y
DY
D000596:Amino Acids / Q000032:analysis; D015152:Blotting, Northern; D002454:Cell Differentiation; D002455:Cell Division / Q000187:drug effects; D003513:Cycloheximide / Q000494:pharmacology; D003600:Cytosol / Q000201:enzymology; D003609:Dactinomycin / Q000494:pharmacology; D004795:Enzyme Stability; D006706:Homeostasis; D006801:Humans; D007700:Kinetics; D015473:Leukemia, Promyelocytic, Acute; D008938:Mitosis; D008970:Molecular Weight; D010748:Phosphopeptides / Q000737:chemistry / Q000302:isolation & purification; D010766:Phosphorylation; D012334:RNA, Neoplasm / Q000235:genetics / Q000302:isolation & purification; D013755:Tetradecanoylphorbol Acetate; D013937:Thymidine Kinase / Q000302:isolation & purification / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D000596:Amino Acids; D010748:Phosphopeptides; D012334:RNA, Neoplasm; D003609:Dactinomycin; D003513:Cycloheximide; D013937:Thymidine Kinase; D013755:Tetradecanoylphorbol Acetate