Enables cysteine-type endopeptidase inhibitor activity involved in apoptotic process. Acts upstream of or within T cell differentiation; T cell receptor signaling pathway; and negative regulation of cysteine-type endopeptidase activity involved in apoptotic process. Predicted to be active in mitochondrial outer membrane. Is expressed in craniocervical region bone; hemolymphoid system; musculature; and respiratory system. Orthologous to human BCL2A1 (BCL2 related protein A1). [provided by Alliance of Genome Resources, Apr 2022]