Bovine brain calmodulin-dependent protein kinase II: molecular mechanisms of autophosphorylation.
A bovine brain calmodulin-dependent protein kinase undergoes autophosphorylation with a maximal incorporation of 10 mol phosphate per mol enzyme. The autophosphorylated enzyme is fully active, independent of Ca2+ and calmodulin. Although the autophosphorylation reaction depends on Ca2+ and calmodulin, it can be rendered Ca(2+)-independent after about 15 seconds when 1 mol phosphate has been incorporated per mol enzyme. This Ca(2+)-independent autophosphorylation is an intramolecular reaction, since mixing of autophosphorylated and non-phosphorylated calmodulin-dependent protein kinase does not result in the Ca(2+)-independent phosphorylation of the non-phosphorylated enzyme. The Ca(2+)-independent autophosphorylation can be inhibited by an exogenous substrate, e.g., casein. The casein phosphorylation activity is approximately proportional to the level of phosphorylation of the enzyme.
Zhang
G Y
GY
Department of Medical Biochemistry, Faculty of Medicine, University of Calgary, Alberta, Canada.
Wang
J H
JH
Sharma
R K
RK
D000818:Animals; D001921:Brain / Q000201:enzymology*; D002118:Calcium / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002364:Caseins / Q000378:metabolism; D002417:Cattle; D004492:Edetic Acid; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*
D002364:Caseins; D004492:Edetic Acid; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002118:Calcium