[8] The BPI fold creates apolar binding pockets that can interact with hydrophobic and amphipathic molecules, such as the acyl carbon chains of lipopolysaccharide found on Gram-negative bacteria, but members of this family may have many other functions.

BPIFB1 was also identified as the LPLUNC1 gene (long-palate lung and nasal epithelium clone 1) in mouse,[11] but subsequently PLUNC proteins were classified as a subfamily of the BPI fold superfamily.

[10] In a systematic analysis of the chicken genome, the Lplunc1(Bpifb1) / Lplunc5(Bpifb5) branch of the gene family was determined to be absent, therefore BPIFB1 and BPIFB5 proteins likely arose only after the speciation of mammals.

[12] In mammals, the BPIFB1 protein is involved in the innate immune response to bacterial exposure in the mucosa of the mouth, nasal cavities, lungs, and digestive tract.

[14] This article incorporates text from the United States National Library of Medicine, which is in the public domain.