Comparison of the enzymatic activities of native and recombinant protein phosphatase-1 toward histone

The activities of native and recombinant rabbit muscle protein phosphatase-1 toward phosphorylated lysine-rich histone and phosphorylase a were compared. The activity of rabbit muscle protein phosphatase-1 toward histone is strongly stimulated by Mn++. In the case of the recombinant enzyme, both phosphorylase phosphatase and histone phosphatase activities exhibit a dependence on Mn++. Examination of the activities of both enzymes assayed under optimal conditions show that they exhibit similar substrate specificities toward histone and phosphorylase, contrary to previous claims (Alessi et al., Eur. J. Biochem. 213, 1055-1066, 1993).