Histone H1 phosphorylated by protein kinase C is a selective substrate for the assay of protein phosphatase 2A in the presence of phosphatase 1.
A protein phosphatase assay, selective for protein phosphatase 2A, has been developed. Bovine histone H1 phosphorylated by protein kinase C and [gamma-32P]ATP, designated H1(C), was tested as the substrate for various preparations of protein phosphatases 1 and 2A. The phosphatase 2A preparations were 10-60-times more active with H1(C) as the substrate when compared to phosphorylase a. The phosphatase 1 enzymes showed very little dephosphorylation of the H1(C) substrate, the activity being less than 5% of the phosphorylase phosphatase activity. This preference and selectivity was demonstrated for purified phosphatase preparations in addition to fresh tissue extracts. The assay provides a rapid, simple assay for the routine analysis of phosphatase 2A in the presence of phosphatase 1, without the use of heat-stable inhibitor proteins.
Jakes
S
S
Department of Pharmacology, Medical College of Ohio, Toledo.
Schlender
K K
KK
D000818:Animals; D002417:Cattle; D004591:Electrophoresis, Polyacrylamide Gel; D006657:Histones / Q000378:metabolism*; D007700:Kinetics; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010762:Phosphorylase a / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism*; D054645:Protein Phosphatase 1; D054648:Protein Phosphatase 2; D051381:Rats
D006657:Histones; D010762:Phosphorylase a; D011493:Protein Kinase C; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D054648:Protein Phosphatase 2