 Sequence similarity with Bcl-2 family members was not detected.Humans and other animals ("Drosophila, Caenorhabditis"), as well as lower eukaryotes ("Dictyostelium, Trypanosoma, Cryptosporidium, Paramecium") encode several BNIP3 paralogues including the human NIP3L, which induces apoptosis by interacting with viral and cellular anti-apoptosis proteins.The right-handed parallel helix-helix structure of the domain with a hydrogen bond-rich "His-Ser" node in the middle of the membrane, accessibility of the node for water, and continuous hydrophilic track across the membrane suggest that the domain can provide an ion-conducting pathway through the membrane.