Ca2+/calmodulin-dependent protein kinases from the neuronal nuclear matrix and post-synaptic density are structurally related.

Abstract

A major Ca2+/calmodulin-dependent protein kinase has been isolated in association with the [rat] neuronal nuclear matrix. Nuclear matrix preparations contain highly phosphorylated polypeptides with MW values of 50,000 and 60,000. These polypeptides were further characterized by peptide and phospho peptide mapping, 2-dimensional isoelectrofocusing/NaDodSO4/PAGE [sodium dodecyl sulfate polyacrylamide gel electrophoresis], and 125I-labeled calmodulin binding. The MW 50,000 and 60,000 polypeptides of the nuclear matrix closely resemble the .alpha. and .beta. subunits, respectively, of the Ca2+/calmodulin-dependent protein kinase of the post-synaptic density. Similar protein kinases apparently mediate the neuronal effects of Ca2+ at the cytosolic, synaptosomal and nuclear levels.