317716n/aENSG00000183566n/anan/aNM_173859n/an/an/aBPI fold containing family A, member 4 (BPIFA4) is a non-human protein encoded by the Bpifa4 gene in mammals such as monkey, cat, and cow but does not appear in rodents and humans.

[13] 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.

Although BPIFA4P is identified as a pseudogene in humans,[7][9] the RNA sequence for a putative protein has been detected at moderate levels in several glands (including salivary and mammillary), skin, and breast cancer.

[15][11] That pattern is consistent with the expression of normal BPIFA4/Latherin found in saliva and sweat of other species such as cow,[4] horse,[5][6] and sheep.

[16] The function of BPIFA4 in those species is associated with BPIFA gene family members' properties of being a surfactant and binding to bacterial lipopolysaccharides.

Further, it is speculated that the presence of a surfactant protein in the saliva of ruminant animals (e.g., cow, horse, sheep) may assist in mastication of large quantities of vegetable matter in their diet.

The BASE gene deposited into US and European databases was eventually recognized as being a member of the BPI/LBP/PLUNC family and subsequently relabeled as BPIFA4P.