BPIFB2 is a member of a BPI fold
protein superfamily defined by the presence of the bactericidal/permeability-increasing protein fold (BPI fold) which is formed by two similar domains in a "boomerang" shape. This superfamily is also known as the
BPI/LBP/PLUNC family or the
BPI/
LPB/
CETP family. 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. Genes for the BPI/LBP/PLUNC superfamily are found in all vertebrate species, including distant
homologs in non-vertebrate species such as insects, mollusks, and roundworms. Within that broad grouping is the BPIF gene family whose members encode the BPI fold
structural motif and are found clustered on a single chromosome, e.g.,
Chromosome 20 in humans, Chromosome 2 in mouse, Chromosome 3 in rat, Chromosome 17 in pig, Chromosome 13 in cow. The BPIF gene family is split into two groupings, BPIFA and BPIFB. In humans, BIPFA consists of 3 protein encoding genes
BPIFA1,
BPIFA2,
BPIFA3, and 1 pseudogene
BPIFA4P; while BPIFB consists of 5 protein encoding genes
BPIFB1,
BPIFB2,
BPIFB3,
BPIFB4,
BPIFB6 and 2 pseudogenes
BPIFB5P,
BPIFB9P. What appears as pseudogenes in humans may appear as fully functional genes in other species. In humans, the
BPIFB2 gene was first identified as a
BPIL3 gene whose encoded protein was called LPLUNC2 (long-palate lung and nasal epithelium clone 2), but subsequently PLUNC proteins were classified as a subfamily of the BPI fold superfamily. In humans, the
BPIFB2 gene is found with other members of the BPI/LBP/PLUNC superfamily in a cluster on Chromosome 20. == Function ==