Ectoprotein kinase activities on non-differentiated and differentiated U-937 cells.
Incubation of intact U-937 cells with 1 micron [gamma-32P] ATP resulted in rapid (10 min) incorporation of radioactivity into phosvitin, kemptide and protein kinase C (PKC)-peptide. The amount of incorporation was dependent on substrate type and concentration, and on incubation time. Staurosporine, H-7 and Mg(2+)-exclusion abolished phosphorylation of kemptide and PKC-peptide but not phosvitin. Cyclic AMP and phorbol ester enhanced kemptide and PKC-peptide phosphorylation. Protein kinase inhibitor (PKI) inhibits only kemptide phosphorylation. Cell differentiation enhanced 2-fold the phosphorylation of phosvitin and PKC-peptide without significant effect on kemptide phosphorylation. ATP concentrations sufficient to trigger changes in intracellular Ca2+ were sufficient to support extracellular phosphorylation reactions. The results suggest the presence of at least three ectokinase activities on U-937 cells that may play important roles in regulating membrane associated specific functions of developing and mature monocytes.
Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
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D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000470:Alkaloids / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002273:Carcinogens / Q000494:pharmacology; D002454:Cell Differentiation; D000242:Cyclic AMP / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007546:Isoquinolines / Q000494:pharmacology; D016403:Lymphoma, Large B-Cell, Diffuse / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology; D009842:Oligopeptides / Q000378:metabolism; D010766:Phosphorylation; D010774:Phosvitin / Q000378:metabolism; D010879:Piperazines / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism*; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D000470:Alkaloids; D002273:Carcinogens; D004791:Enzyme Inhibitors; D007546:Isoquinolines; D009842:Oligopeptides; D010879:Piperazines; C037642:kemptide; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000255:Adenosine Triphosphate; D010774:Phosvitin; D000242:Cyclic AMP; D011494:Protein Kinases; C034454:ectoprotein kinase; D011493:Protein Kinase C; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium