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Updated: Aug 11, 2026

Assaying Protein Kinase Activity with Radiolabeled ATP
Published on: May 26, 2017
The ATP,Mg-dependent protein phosphatase: regulation by casein kinase-1
P Agostinis1, J R Vandenheede, J Goris
1Afdeling Biochemie, Faculteit Geneeskunde, Katholieke Universiteit te Leuven, Belgium.
Abstract:
The free modulator subunit of the ATP,Mg-dependent phosphatase is phosphorylated up to 1 mol per mol by casein kinase-1, up to 1.85 mol per mol after dephosphorylation by the PCSH1 phosphatase, but 10-fold less when purified in the presence of NaF, suggesting an in vivo phosphorylation of the casein kinase-1 sites. Peptide mapping of 32P-modulator labeled by casein kinase-1 or -2 shows a different phosphorylation pattern. Phosphorylation of the inactive phosphatase by casein kinase-1 prevents the subsequent kinase FA-mediated activation, while it does not impair the activated phosphatase.
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