Apoptosis-inducing protein that can overcome BCL2 suppression. May play a role in repartitioning calcium between the two major intracellular calcium stores in association with BCL2. Involved in mitochondrial quality control via its interaction with SPATA18/MIEAP: in response to mitochondrial damage, participates in mitochondrial protein catabolic process (also named MALM) leading to the degradation of damaged proteins inside mitochondria. The physical interaction of SPATA18/MIEAP, BNIP3 and BNIP3L/NIX at the mitochondrial outer membrane regulates the opening of a pore in the mitochondrial double membrane in order to mediate the translocation of lysosomal proteins from the cytoplasm to the mitochondrial matrix. Plays an important role in the calprotectin (S100A8/A9)-induced cell death pathway. Homodimer. Binds to BCL2. Interacts with BNIP3L and ACAA2. Interacts (via BH3 domain) with SPATA18 (via coiled-coil domains). Interacts with BOK; promotes BOK oligomerization (PubMed:15868100). (Microbial infection) Interacts with adenovirus E1B 19 kDa protein. (Microbial infection) Interacts with Epstein-Barr virus BHRF1. Coexpression with the EIB 19-kDa protein results in a shift in NIP3 localization pattern to the nuclear envelope. Colocalizes with ACAA2 in the mitochondria. Colocalizes with SPATA18 at the mitochondrion outer membrane. Belongs to the NIP3 family.