Ca2+/calmodulin-dependent protein kinase II. Identification of a regulatory autophosphorylation site adjacent to the inhibitory and calmodulin-binding domains.
Ca2+/calmodulin-dependent protein kinase II (CaM-kinase II) autophosphorylated under limiting conditions (7 microM [gamma-32P]ATP, 500 microM magnesium acetate, 4 degrees C) was analyzed by CNBr cleavage and peptide mapping to determine the site of autophosphorylation that brings about transition of the kinase to the Ca2+-independent form. Reverse phase high performance liquid chromatography (HPLC) (C3) revealed one major CN-Br 32P-peptide (CB1) that eluted at about 6% propanol. This peptide contained [32P]threonine, but almost no [32P]serine, and migrated as a single band (Mr = 3000-3500) in polyacrylamide gels run in the presence of urea and sodium dodecyl sulfate. The properties of CB1 were compared to the properties of a 26-residue synthetic peptide containing the CaM-binding and inhibitory domains as well as a consensus phosphorylation sequence (-Arg-Gln-Glu-Thr-) of rat brain CaM-kinase II (residues 282-307 and 283-308 of the alpha and beta subunits, respectively). CB1 and the synthetic peptide comigrated in urea/sodium dodecyl sulfate gels, co-eluted from reverse phase HPLC (C3 and C18) and from Sephadex G-50, and exhibited Ca2+-dependent calmodulin-binding properties. When the two peptides were subjected to automated Edman sequence analysis, both exhibited a burst of 32P release at cycle 5, which is consistent with the expected amino-terminal sequence of the two peptides, i.e. His-Arg-Gln-Glu-Thr(PO4)-. These findings indicate that autophosphorylation of Thr286 (alpha subunit) and Thr287 (beta subunit) is responsible for transition of CaM-kinase II to the Ca2+-independent form.
Schworer
C M
CM
Howard Hughes Medical Institute, Vanderbilt University School of Medicine, Nashville, Tennessee 37232.
Colbran
R J
RJ
Keefer
J R
JR
Soderling
T R
TR
D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000201:enzymology; D002118:Calcium / Q000494:pharmacology*; D002147:Calmodulin / Q000494:pharmacology*; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D003488:Cyanogen Bromide; D004591:Electrophoresis, Polyacrylamide Gel; D007700:Kinetics; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D010769:Phosphothreonine / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats
D002147:Calmodulin; D010446:Peptide Fragments; D010769:Phosphothreonine; D010768:Phosphoserine; D000255:Adenosine Triphosphate; D011494:Protein Kinases; D003488:Cyanogen Bromide; D002118:Calcium