Monoclonal antibody against a multifunctional calmodulin-dependent protein kinase from rat brain and the tissue distribution of the enzyme

We have prepared hybridoma cells that produce monoclonal antibody against a multifunctional calmodulin-dependent protein kinase (calmodulin-kinase) from rat brain. The monoclonal antibody was of the IgM class and cross-reacted with the 49 K-subunit of the enzyme but not with the 60 K-subunit. There was no cross-reaction with the Ca²⁺-calmodulin-dependent phosphodiesterase, calcineurin and other calmodulin-binding proteins from the brain. The monoclonal antibody was used to study regional distribution of calmodulin-kinase in the brain. The 49 K subunit was detected in all brain regions examined, but was found predominantly in cerebral cortex, hippocampus and striatum. Further analysis of various rat tissues by immunoblotting revealed the presence of immunoreactive proteins with M(r) 52,000 in the spleen, stomach, pancreas, lung and adipose tissue and with the M(r) 55,000 in the skeletal muscle and heart. In addition, the findings obtained by immunoreactivity were consistent with those determined by enzyme activity. The results suggest that calmodulin-kinase is widely distributed in the tissues.