Autophosphorylation of Ca2+/calmodulin-dependent protein kinase II: effects on interaction between enzyme and substrate.
Characteristics of the autophosphorylation of Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) from the cytosol and in the postsynaptic densities (PSD) of rat brain were investigated. Several proteins were surveyed for their abilities to serve as a substrate for non-autophosphorylated and autophosphorylated CaM kinase IIs from the cytosol and PSD. The tested substrates were separated into two groups. Autophosphorylation of the kinase slightly decreased or did not change its activities towards substrates of the first group: myosin light chain of chicken gizzard, synapsin I, tau factor and microtubule-associated protein 2. In contrast, autophosphorylation of the enzyme increased its activities towards substrates of the second group: syntide-2, histone H1, calcineurin and myelin basic protein. The Ca2+/calmodulin-independent kinase activity increased by autophosphorylation with any of substrates tested. Similar results were obtained with the cytosolic and PSD CaM kinase II. Trifluoperazine and mastoparan, calmodulin binding antagonists, inhibited the activity of the non-autophosphorylated CaM kinase II, but had no effect or only a slight inhibitory effect on the activity of the autophosphorylated CaM kinase II, indicating that the autophosphorylated kinase has no requirement for calmodulin for Ca(2+)-dependent activity and/or a higher affinity for calmodulin The results suggest that the autophosphorylation of CaM kinase II is a subtle mechanism for regulating the interaction between the enzyme and substrate.
Yasugawa
S
S
Department of Neuropsychiatry, Kumamoto University Medical School, Japan.
Fukunaga
K
K
Yamamoto
H
H
Miyakawa
T
T
Miyamoto
E
E
D000818:Animals; D001921:Brain / Q000201:enzymology; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002417:Cattle; D003600:Cytosol / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D036341:Intercellular Signaling Peptides and Proteins; D007700:Kinetics; D010455:Peptides; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000378:metabolism*; D013379:Substrate Specificity; D014268:Trifluoperazine / Q000494:pharmacology; D014862:Wasp Venoms / Q000494:pharmacology
D004791:Enzyme Inhibitors; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D047428:Protein Kinase Inhibitors; D014862:Wasp Venoms; D014268:Trifluoperazine; C037500:mastoparan; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases