Phosphorylation and dephosphorylation of the regulatory subunit of cyclic 3',5'-monophosphate-dependent protein kinase (type II) in vivo and in vitro.
A phosphorylated regulatory subunit of cyclic AMP-dependent protein kinase (type II) was purified to homogeneity from inorganic [32P]phosphate-injected rats. A new method of measuring the phosphorylation reaction was developed. It was found that this regulatory subunit was phosphorylated in cells and comprised 60, 82 and 55% of the total regulatory subunit in brain, heart and liver cytosol fractions from rats, respectively. Dephosphorylation was stimuated by cyclic nucleotides. The Ka values for cyclic AMP and cyclic IMP were 0.30 and 1.0 microM, respectively. Purified phosphoprotein phosphatase could dephosphorylate the regulatory subunit and this reaction was also stimulated by cyclic nucleotides with similar Ka values. The inhibitors of phosphoprotein phosphatase, NaF and ZnCl2, protected against dephosphorylation unless ADP or cyclic AMP were present.
D000244:Adenosine Diphosphate / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism; D002712:Chlorides / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004792:Enzyme Precursors / Q000378:metabolism*; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000378:metabolism*; D008099:Liver / Q000378:metabolism; D008297:Male; D009206:Myocardium / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats; D012969:Sodium Fluoride / Q000494:pharmacology; D015032:Zinc / Q000494:pharmacology
D002712:Chlorides; D004792:Enzyme Precursors; D007527:Isoenzymes; D000244:Adenosine Diphosphate; D012969:Sodium Fluoride; D000242:Cyclic AMP; D011494:Protein Kinases; D015032:Zinc