Isoenzyme transitions of creatine phosphokinase, aldolase and phosphoglycerate mutase in differentiating mouse cells

Extracts of embryonic mouse tissues (skeletal, cardiac and smooth muscle, and brain) were analysed by Cellogel electrophoresis for their isoenzymic distributions of three enzymes, creatine phosphokinase, aldolase and phosphoglycerate mutase. Embryonic tissues from the 12th day to the end of gestation were examined for isoenzyme transitions, and it was found that the adult forms of these enzymes appeared during gestation. Extracts from cloned teratocarcinoma cells were similarly examined in order to determine their degree of bio-chemical differentiation. Undifferentiated embryonal carcinoma cells contained only the early embryonic forms of all three enzymes, while differentiated cells formed in vivo, and in some cases in vitro, started to express the adult types of creatine phosphokinase and aldolase. Thus, biochemical parallels have been demonstrated between developing embryonic tissues and teratocarcinoma cells differentiating in vitro.