Pyruvate kinase studies in the granulocyte-macrophage lineage during in vitro differentiation have been performed using culture techniques on GM-CFC cells and a study has also been done in bone marrow cells.
The enzyme exhibits biphasic behaviour with respect to both of its substrates in cells derived from in vitro cultures at 5 and 7 days of incubation period. However in bone marrow cells these kinetics are only observed for ADP.
The different kinetic behaviour of pyruvate kinase toward Fru-1,6-P2, Ala, Phe and ATP in the three cellular populations allows us to conclude that the expression of pyruvate kinase is associated with the differentiation of these cells.
Abbreviations GM-CFC, granulocyte-macrophage colony forming cells; PK, pyruvate kinase; CFU-E, Colony Forming Units Erythroid; Ew, Error weight; PEP, phosphoenolpyruvate; Fru-1,6-P2, fructose 1,6-bisphosphate; Ala, L-alanine; Phe, L-phenylanine; 5 GM, granulocytemacrophage colonies obtained after 5 days incubation; 7 GM, granulocyte-macrophage colonies obtained after 7 days incubation; h, Hill coefficient; S0,5, substrate concentration that yields half-maximal velocity