Reversible activation and inactivation of phosphofructokinase from Ascaris suum by the action of tissue-homologous protein phosphorylating and dephosphorylating enzymes.

In the presence of ATP-Mg2+, purified phosphofructokinase from Ascaris suum muscle was effectively phosphorylated and activated in vitro by a protein kinase purified from the same tissue. Both effects were reversed by the action of a purified protein phosphatase from the same tissue. The findings suggest the presence of a highly potent interconversion mechanism for phosphofructokinase in the muscle of the parasitic nematode.