Inactivation of phosphofructokinase 2 by cyclic AMP - dependent protein kinase

Treatment with the catalytic subunit of cyclic AMP-dependent protein kinase induced the following modifications in the kinetic properties of purified phosphofructokinase 2. The affinity for Fru-6-P, the V_max and the stimulatory effect of P_i were decreased; the inhibitory actions of P-enol-pyruvate and citrate were increased; the pH activity curve, measured in the presence of 5 mM Fru-6-P and 5 mM P_i was modified in the respect that the peak of activity normally measured at pH 6.6 was abolished whereas no effect of the treatment was observed at pH 8. Similar changes in the properties of phosphofructokinase 2 were also observed in a crude preparation obtained from hepatocytes incubated with glucagon.