Early postnatal development of calmodulin-dependent protein kinase II in rat brain.

The postnatal levels of the alpha- (Mr 50,000) and beta- (Mr 58,000/60,000) subunits of type II calmodulin-dependent protein kinase were investigated in cytosolic, cytoskeletal and nuclear subfractions of rat brain. Substantial amounts of the beta-subunit were present neonatally, especially in the cytoplasm; both subunits increased markedly during the subsequent three weeks with alpha-preponderance in the cortex and midbrain. The development of the alpha-subunit was attenuated in the cerebellum and brain stem, resulting in a relative excess of the beta-subunit. Primary neuronal cultures from fetal brain initially displayed low enzyme content, followed by an increase in the levels of the beta- but not alpha-subunit. Regulation of the cellular content of type II calmodulin-dependent protein kinase may be relevant to neuronal differentiation.