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.
Department of Medical Biochemistry, Faculty of Medicine, University of Calgary, Alberta, Canada.
G Y
GY
Zhang
J H
JH
Wang
R K
RK
Sharma
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