Inactivation of Ca2+/calmodulin-dependent protein kinase IV by Ca2+/calmodulin and restoration of the activity by Mg2+/EGTA.
The activity of calmodulin-dependent protein kinase IV (CaM-kinase IV) was progressively decreased by incubation at 30 degrees C with calmodulin in the presence of Ca2+, becoming one-half to one-fifth of the original activity within several minutes. The amount of calmodulin necessary to produce the maximal inactivation was approximately 1 mol for 1 mol of the enzyme. The inactivation of CaM-kinase IV by Ca2+/calmodulin was prevented by ATP in the presence of Mg2+, but such protection was not observed with either of the two alone or with a peptide substrate such as syntide-2. The activity of the calmodulin-inactivated enzyme was increased by incubation at 30 degrees C with Mg2+ in the presence of EGTA, being completely restored to the original level within several minutes, indicating that the Ca2+/calmodulin-induced inactivation of the enzyme was not due to irreversible denaturation of the enzyme. Both the inactivation of CaM-kinase IV by Ca2+/calmodulin and the restoration of its activity by Mg2+/EGTA were time- and temperature-dependent reactions. Kinetic analysis revealed that the alterations of the enzyme activity were due mainly to changes in Vmax of the enzyme.
Kitani
T
T
Department of Biochemistry, Asahikawa Medical College, Hokkaido.
Okuno
S
S
Fujisawa
H
H
D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000737:chemistry / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism / Q000494:pharmacology*; D002412:Cations; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000378:metabolism / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism / Q000494:pharmacology*; D051381:Rats; D013696:Temperature; D013997:Time Factors
D002147:Calmodulin; D002412:Cations; D004533:Egtazic Acid; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C517686:Camk4 protein, rat; D008274:Magnesium; D002118:Calcium