The antiserum against Ca2+-ATPase, isoform 2, was produced in rabbits by immunization with the N-terminal sequence-specific peptide of the human pump as epitope. It recognizes the corresponding proteins in human, rat and mouse tissue. The antibody was evaluated for specificity and potency : a) by Biotin-Avidin labelling of cryostatesections of 4% paraformaldehyde fixed tissue and b) by immunoenzymatic labelling of Western blots of brain membranes or primary nerve cell cultures. It can also be used for immunoprecipitation. The serum was inactivated at 50°C for 30 minutes.