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Regulatory Properties of Calcium/Calmodulin‐Dependent Protein Kinase II in Rat Brain Postsynaptic Densities
Author(s) -
Rich Devra P.,
Cdlbran Roger J.,
Schworer Charles M.,
Soderling Thomas R.
Publication year - 1989
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1989.tb11777.x
Subject(s) - autophosphorylation , protein kinase a , calmodulin , mitogen activated protein kinase kinase , biochemistry , kinase , phosphorylation , chemistry , casein kinase 2 , biology , map2k7 , cyclin dependent kinase 2 , enzyme
Calcium/calmodulin (CaM)‐dependent protein kinase II (CaM‐kinase II) contained within the postsynaptic density (PSD) was shown to become partially Ca 2+ ‐indepen‐dent following initial activation by Ca 2+ /CaM. Generation of this Ca 2+ ‐independent species was dependent upon auto‐phosphorylation of both subunits of the enzynme in the presence of Mg 2+ /ATP/Ca 2+ /CaM and attained a maximal value of 74 ± 5% of the total activity within 1–2 min. Subsequent to the generation of this partially Ca 2+ ‐independent form of PSD CaM‐kinase II, addition of EGTA to the autophos‐phorylation reaction resulted in further stimulation of 32 PO 4 incorporation into both kinase subunits and a loss of stimulation of the kinase by Ca 2+ /CaM. Examination of the sites of Ca 2+ ‐dependent autophosphorylation by phosphoamino acid analysis and peptide mapping of both kinase subunits suggested that phosphorylation of Thr 286/287 of the α‐ and β‐subunits, respectively, may be responsible for the transition of PSD CaM‐kinase II to the Ca 2+ ‐independent species. A synthetic peptide 281–309 corresponding to a portion of the regulatory domain (residues 281–314) of the soluble kinase inhibited syntide‐2 phosphorylation by the Ca 2+ ‐independent form of PSD CaM‐kinase II (IC 50 = 3.6 ± 0.8 μ M). Binding of Ca 2+ /CaM to peptide 281–309 abolished its inhibitory property. Phosphorylation of Thr 286 in peptide 281–309 also decreased its inhibitory potency. These data suggest that CaM‐kinase II in the PSD possesses regulatory properties and mechanisms of activation similar to the cytosolic form of CaM‐kinase II.