In the proposed investigation we intend to extend our studies of a low-molecular-weight calcium-binding protein which we have identified in the optic lobe of the squid. Our studies to date have shown that this protein is present in the optic lobe in large amounts, comparable to the amounts of calmodulin present, yet is chemically and functionally distinct from squid calmodulin, which we have also isolated. We have raised a specific antibody to the squid protein and have found no cross-reaction with other members of the family of high-affinity, intracellular calcium-binding proteins from squid or other species. The proposed study has two long-term objectives. The first is to characterize the physicochemical and structural properties of the squid protein using spectroscopic, sequencing and crystallographic procedures. The second is to characterize the functional properties of the protein, using immunological techniques to localize the protein in squid nervous tissue, and using affinity chromatography, gel blotting, gel overlay and other procedures, to identify interacting proteins or other substances. An understanding of the structure and function of this protein will add to our knowledge on the mode of action of high-affinity calcium-binding proteins as a class, and will provide further insight into processes involving calcium regulation in squid nervous tissue. It will also be valuable in interpreting data already obtained by others concerning calcium regulation and calcium metabolism in this tissue. Since the squid has provided an important model for characterizing many of the events involved in nervous function an improved understanding of its properties, its similarities and dissimilarities from the vertebrate system, will be valuable in extending our understanding of vertebrate nervous function and ultimately disorders of the human nervous system.
