Conversion of pyruvate kinase (PK) isozymes during development of normal and PK deficient erythroblasts.

Using immunofluorescent antibody techniques, conversion of pyruvate kinase (PK) isozymes during the maturation of erythroblasts was studied. In normal subjects, M2-type PK was clearly seen at the proerythroblast stage, then markedly declined with cell maturation, whereas L-type PK continued to increase. In classical type PK deficiency, M2-type PK was still clearly seen in orthochromatic erythroblasts, whereas L-type PK was scarcely detected during maturation. In other PK deficiency cases, change of L-type PK showed a similar pattern to that of normal while M2-type PK was still clearly seen at the later stage of maturation as in the classical type. In K-562 human leukemia cell line, M2-type PK declined and L-type PK increased in parallel with hemoglobin synthesis by addition of hemin, an inducer for differentiation into erythroblasts. Hemoglobin synthesis and L-type PK production appear to have interrelation during the differentiation and maturation of erythroblasts.