Calcium Calmodulin Dependent Phosphorylation of Proteins: Fetal Cortical Neurons and Adult Cortex

In the present investigation, changes in the calcium calmodulin-dependent phosphorylation of proteins have been examined in murine fetal cortical neurons and adult cortex. An ∼80-kD protein in the fetal neurons was not phosphorylated/dephosphorylated in a calmodulin-dependent manner. However, this protein was phosphorylated by PMA both in the presence and absence of calcium. These data suggest that calmodulin inhibits the phosphorylation of a ∼80-kD protein by inhibiting PKC in murine fetal cortical neurons but not in the adult cortex. More importantly, we demonstrate that the calmodulin-mediated inhibition of phosphorylation was restored by preincubating the cortical neurons with KN-62, a CaM kinase inhibitor.