Protein phosphatase 2A is a specific protamine-kinase-inactivating phosphatase.
Purified preparations of a protamine protein kinase from bovine kidney cytosol [Damuni, Amick & Sneed (1989) J. Biol. Chem. 264, 6412-6416] were inactivated after incubation with near-homogeneous preparations of protein phosphatase 2A1 and protein phosphatase 2A2. These protein phosphatase 2A-mediated inactivations of the protamine kinase were unaffected by highly purified preparations of inhibitor 2, but were prevented when the incubations were performed in the presence of 100 nM microcystin-LR, 100 nM okadaic acid or 0.2 mM-ATP. By contrast, highly purified preparations of protein phosphatase 2B, protein phosphatase 2C, the catalytic subunit of protein phosphatase 1, and two forms of a protein tyrosine phosphatase, designated PTPase 1B and T-cell PTPase, had little effect, if any, on protamine kinase activity. Purified preparations of the protamine kinase did not react with anti-phosphotyrosine antibodies, as determined by Western blotting and immunoprecipitation analysis. The results indicate that protein phosphatase 2A is a specific protamine-kinase-inactivating phosphatase.
Amick
G D
GD
Department of Biological Sciences, University of South Carolina, Columbia 29208.
Reddy
S A
SA
Damuni
Z
Z
D000818:Animals; D002417:Cattle; D004926:Escherichia coli; D007700:Kinetics; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D006656:Protamine Kinase; D047428:Protein Kinase Inhibitors; D054645:Protein Phosphatase 1; D054648:Protein Phosphatase 2
D047428:Protein Kinase Inhibitors; D006656:Protamine Kinase; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D054648:Protein Phosphatase 2