Bcl-2/adenovirus E1B 19kD protein-interacting protein 3-like (BNIP3L) also known as BNIP3 alpha and NIP3-like protein X (Nix), is a proapoptotic member of BNIP3 protein family. BNIP3L is a functional homolog of BNIP3 and both proteins contain a single Bcl-2 homology 3 (BH3) domain. BNIP3L is a 219aa, 24kD (predicted) protein that contains a C-terminal transmembrane domain required for mitochondrial localization, homodimerisation, and regulation of its proapoptotic function. BNIP3L may antagonize the activity of BCL2 family antiapoptic proteins by directly interactacting with proteins such as viral E1B-19K and cellular Bcl-2 and Bcl-xL. BNIP3L shares 56% aa sequence identity with BNIP3 and 98% with mouse and rat BNIP3L.