Four monoclonal antibodies generated against the Type II CaM kinase have been characterized. Two of these antibodies were used to confirm that both alpha and beta subunits were part of the holoenzyme complex. I also developed liquid phase and solid phase radioimmunoassays for the kinase.
With the solid phase radioimmunoassay, the distribution of the kinase in rat brain was examined. This study revealed that the concentration of the kinase varies markedly in different brain regions. It is most highly concentrated in the telencephalon where it comprises approximately 2% of total hippocampal protein, 1.3% of cortical protein and 0.7% of striatal protein. It is less concentrated in lower brain regions ranging from 0.3% of hypothalamic protein to 0.1% of protein in the pons/medulla. The unusually high concentration of the kinase in telencephalic regions may confer upon their neurons specialized responses to calcium that are different from those of neurons in lower brain regions.
The association of the kinase with elements of the cytoskeleton was also investigated. The results of this study showed that autophosphorylation causes an increase in the association of the enzyme with taxol-polymerized microtubules and F-actin. This increase in association was reversed by dephosphorylating phosphokinase with protein phosphatase. These results suggest that autophosphorylation could constitute a mechanism for the regulation of the subcellular associations of the Type II CaM kinase by neuronal activity.
