PHOSPHORYLATION AND INHIBITION OF HUMAN-ERYTHROCYTE PYRUVATE-KINASE BY ERYTHROCYTE-MEMBRANES

The enzymatic activity of human erythrocyte pyruvate kinase was found to decrease on incubation of the purified enzyme with red blood cell ghosts, ATP and cAMP. If [32P]γATP was used radioactivity was found associated with the protein after gel electrophoresis. Various effectors protected the enzyme against phosphorylation. Treatment of the modified enzyme with a protein phosphatase restored enzymatic activity and also caused the loss of the radioactive label. Modification of the pyruvate kinase in this way altered the affinity of the enzyme for one of its substrates (phosphoenolpyruvate), but the binding of the other substrate (ADP) was unaffected. © 1979.