Autophosphorylation of calmodulin-dependent protein kinase IV from rat cerebral cortex.
Calmodulin-dependent protein kinase IV from rat cerebral cortex undergoes autophosphorylation in response to Ca2+ and calmodulin, resulting in its marked enzymatic activation. Autophosphorylation occurred at several sites on CaM-kinase IV, depending upon the enzyme concentration. Among them, Ser437 was almost exclusively phosphorylated at enzyme concentrations lower than 10 micrograms/ml, and autophosphorylation at Ser437 was responsible for marked activation of the enzyme through decreases in the Km values for its substrates and an increase in the Vmax value. The Ca2+/calmodulin-independent activity of CaM-kinase IV was also markedly stimulated by autophosphorylation, but even after autophosphorylation it amounted only about 17% of the total enzyme activity detected in the presence of Ca2+/calmodulin.
Kameshita
I
I
Department of Biochemistry, Asahikawa Medical College, Hokkaido.
Fujisawa
H
H
D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002147:Calmodulin / Q000494:pharmacology; D002540:Cerebral Cortex / Q000201:enzymology*; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D007700:Kinetics; D008969:Molecular Sequence Data; D010766:Phosphorylation / Q000187:drug effects; D011494:Protein Kinases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D012694:Serine / Q000378:metabolism
D002147:Calmodulin; D012694:Serine; D011494:Protein Kinases; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C517686:Camk4 protein, rat; D002118:Calcium