Identification of a Ca2+-ATPase in cerebellar Purkinje cells.

The expression of a sarcoplasmic reticulum (SR)-like Ca2+-ATPase was studied in the adult chicken cerebellum. A monoclonal antibody. CaS/C1-IgG, specific for the cardiac/slow-twitch skeletal muscle SR Ca2+-ATPase, was used as a probe of protein expression. An immunoblot analysis showed that CaS/C1-IgG recognized similar size polypeptides in adult chicken heart and cerebellum. CaS/C1-IgG recognized fragments of similar size after limited tryptic digestion of cardiac and cerebellar membranes. A two-dimensional alpha-chymotryptic peptide map analysis demonstrated that the cardiac and cerebellar Ca2+-ATPases were structurally very similar. Immunofluorescence microscopy localized the cerebellar Ca2+-ATPase to Purkinje cell bodies and dendritic trees. These results suggest that the well-known Ca2+ uptake system of skeletal and cardiac muscle SR has a remarkably similar counterpart in some neurons.