Enables calcium-dependent cysteine-type endopeptidase inhibitor activity and protease binding activity. Involved in several processes, including animal organ development; egg activation; and myoblast fusion. Located in several cellular components, including cytoplasm; nucleus; and postsynaptic density. Used to study brain ischemia. Human ortholog(s) of this gene implicated in Parkinson's disease; autoimmune disease (multiple); congenital myasthenic syndrome 1A; and vasculitis. Orthologous to human CAST (calpastatin). [provided by Alliance of Genome Resources, Apr 2022]