This project represents an investigation of the role of calcium binding proteins, which underwrite calcium actions, in nervous tissue. We are focusing on calmodulin, a protein which activates several calcium-dependent enzymes in mammalian brain. Calmodulin levels are higher in electric organ of the electric eel than in any mammalian tissue, yet in this tissue calmodulin does not activate those enzymes which are calmodulin sensitive in rat or pig brain. We are attempting to determine the biochemical role of calmodulin in electric tissue, as we believe that this information will lead to new insights into how this protein regulates brain function in higher organisms. Studies of post-translational modification and regulation of membrane binding of calmodulin are designed to address these questions.