Metabolic control of glycolysis in normal and tumor permeabilized cells

Our previous reports have presented evidence suggesting the existence in tumor cells of a second control site of glycolysis of pyruvate kinase as a competition for adenosine diphosphate between this enzyme and mitochondria, which is responsible for the Crabtree effect. Now, by using cells partially permeabilized to nucleotides and phosphorylated substrates, we provide evidence supporting the existence in hepatocytes of a partial control by adenosine triphosphate at phosphofructokinase, which is followed by the total control by adenosine triphosphate at pyruvate kinase. The partial or nonoperation of this second site in Ehrlich ascites tumor cells appears to be the cause for the characteristic aerobic glycolysis, Crabtree effect, and low Pasteur effect of these cells.