Developmental changes in the levels of Ca2+/calmodulin-dependent protein kinase II alpha and beta proteins in soluble and particulate fractions of the rat brain.

Developmental changes in Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) have been immunochemically examined in the forebrain, cerebellum and brainstem of the rat using antibodies against its alpha or beta protein. The concentration of alpha and beta proteins varied markedly in different brain regions at increasing postnatal ages. In early postnatal brain, the concentration of the alpha and beta proteins was low, and a large increase was observed between postnatal days 10 and 30. The maximum expression of the alpha protein was in the order of 6.01, 2.33 and 0.168 micrograms/mg of forebrain, brainstem and cerebellum proteins respectively, in the soluble or particulate fraction. On the other hand, that of the beta protein was in the order of 1.81, 0.495 and 0.291 micrograms/mg of forebrain, cerebellum or brainstem protein. The ratio of alpha and beta proteins also differed in the soluble and particulate fractions. The maximum expression of the alpha protein was observed at day 30 in soluble and particulate fractions of forebrain, and at day 20 in those of the brainstem. The major alpha protein peak was observed on or after day 30 in particulate and soluble fractions from cerebellum, respectively. The maximum expression of the beta protein was observed at day 20 in soluble and particulate fractions of the forebrain as well as in soluble fraction of the cerebellum, and was observed at day 30 in the particulate fraction of cerebellum. The expression of the alpha and beta proteins roughly correlated with the CaM kinase II activity from forebrain and brainstem.