Glycolytic enzymes of an erythroleukemic cell line, K562, before and after hemoglobin induction

The enzyme activities and isozyme distribution of some glycolytic enzymes were studied in the K562 cell line before and after induction of hemoglobin formation. Special attention was paid to the three regulator enzymes of glycolysis, hexokinase, phosphofructokinase and pyruvate kinase. Results for the K562 cell line were compared with those for the mature red cell. K562 cells exhibit a relatively low phosphofructokinase and high pyruvate kinase activity. Electrophoresis of hexokinase shows the presence of two bands in the HK I region. HK II is also present, probably as a result of culture conditions. Only 15% of the total hexokinase activity is mitochondrial bound. Phosphofructokinase in K562 cells is mainly composed of the L- and F-types of which the F-type is characteristic for platelets and granulocytes and not for erythrocytes. In the electrophoretic pattern of pyruvate kinase a predominant K4 band besides three hybrids were found. The hybrids were demonstrated to contain L-type subunits of pyruvate kinase, which means a new erythroid marker of K562 cells, as the red cell is the only blood cell that contains L-type pyruvate kinase. Induction experiments with hemin, ARA-C and mitomycin-C gave rise to more than 85% benzidine positive cells after 11 days of culture. The isozyme composition of pyruvate kinase did not change after induction. HK II disappears after induction with ARA-C and mitomycin-C but not with hemin. The results support the idea of the multipotential features of the K562 cell line.