14.23 kb on reverse strand; 6 exons

mRNA in MCF-7 cells are 1.7kb (major) and 1.5 kb (minor) and 1.3 kb (minor).

194 amino acids; 1 BH3 domain and 1 TM domain; BH3 only Bcl2 family member. The TM domain and C-terminal tail are essential for mitochondrial membrane localization and proapoptotic function. The predicted molecular weight is 21.5 kDa. BNIP3 migrates as 30 kDa monomeric form and 60 kDa dimeric form on SDS-PAGE.

BNIP3 is detected in mouse oviduct, uterus, spleen, lung, stomach, brain, seminal, lacrimal, submaxillary, heart, kidney, liver. It can be detected in cell lines such as HeLa, 293T, RAW264.7 and K562 cells. Its expression can be induced in both normal and cancer tissues that experience hypoxia or hypoxia-like conditions. Other stimuli, such as nitric oxide or arsenic trioxide, are also reported to induce BNIP3 expression.

Outer mitochondrial membrane

Proapoptotic protein;
BNIP3 leads to opening of the mitochondrial permeability transition pore (PTP) thereby abolishing the proton electrochemical gradient and this is followed by chromatin condensation and DNA fragmentation. BNIP3 leads necrosis-like apoptosis. Unusually to the other Bcl-2 family proteins, the BNIP3-induced cell death depends not on BH3 domain but on C-terminal TM domain. BNIP3-induced cell death is known to be independent the nuclear translocation of AIF. However, whether caspase activation and cytochrome c release are involved in the cell death remains controversial. BNIP3 can induce autophagy. However whether the consequence of the autophagy is the cell death or survival remains to be established.
Since BNIP3 is induced by hypoxia through transcription factor HIF-1, it was postulated to play a role in hypoxia-induced cell death. Hypoxia-induced acidosis augments the proapoptotic function of BNIP3.

The close homologue: BNIP3L/ BNIP3a/ Nix/ B5 (8q21)
The BH3-only Bcl2 family members: BBC3/PUMA (19q13), BCL2L11/BIM/BOD (2Q13), BID (22q11), BIK/NBK/BBC1 (22q13), BLK (8q23), BMF (15Q14), HRK/DP5/BID3 (12q24), PMAIP1/NOXA (18q21)