Characterization of mouse neuronal Ca²⁺/calmodulin kinase II inhibitor α

Abstract

We have overexpressed an 8.5-kDa mouse Ca²⁺/calmodulin kinase II inhibitor a protein (mCaMKIINα) in Escherichia coli and demonstrate that the recombinant protein is a potent inhibitor of Ca²⁺/calmodulin kinase II (CaMKII) in vitro. However, antibodies raised against recombinant mCaMKIINα react with an ~7-kDa protein present in mouse brain. The pattern of expression of the ~37-kDa protein is similar to that of mCaMKIINα mRNA as both are expressed in normal but not Japanese encephalitis virus (JEV)-infected mouse brain. Subcellular localization studies indicate that the ~37-kDa protein is present in the post-synaptic density (PSD) where mCaMKIIα is known to perform key regulatory functions. We conclude that the ~37-kDa protein identified in this study is mCaMKIINα and its localization in the PSD indicates a novel role for this protein in the regulation of neuronal CaMKIIα.