Protein kinase C in human brain and its inhibition by calmodulin

Protein kinase C is a ubiquitous enzyme which is especially concentrated in brain tissue and which has been reported to have a key role in the regulation of neuronal activity. Substrates for this kinase were studied in frozen postmortem human cortex. Two major protein substrates with mol. wts. of 86,000 and 67,000 Da were found in the cytosol the cytosol fraction. Calmodulin was found to inhibit phosphorylation of these two proteins.