Purification of the catalytic subunit of protein phosphatase-1 from

The catalytic subunit of phosphatase-1 has been purified from Drosophila melanogaster by precipitation with (NH4)2SO4 and ethanol, by affinity chromatography on heparin-Sepharose and by fast protein liquid chromatography on Mono Q beads. The preparation is homogeneous as tested by SDS gel electrophoresis and has a molecular mass of 33,000. The phosphatase specifically dephosphorylates the beta subunit of phosphorylase kinase. Its phosphorylase phosphatase activity is inhibited by inhibitor-1, inhibitor-2, protamine and histone H2B while is stimulated by histone H1.