BPI Gene - Bactericidal/Permeability-Increasing Protein | NCBI, UniProt, OMIM

BPI (bactericidal/permeability-increasing protein) is a 55-60 kDa cationic protein stored in the azurophilic granules of neutrophils. It exerts potent bactericidal activity against Gram-negative bacteria by binding to lipopolysaccharide (LPS) on the bacterial outer membrane, disrupting membrane integrity, and neutralizing endotoxin. BPI also opsonizes bacteria and modulates inflammatory responses. The gene is located on chromosome 20q11.23 and is primarily expressed in myeloid cells.

Tissue Expression

Cell Line Expression

Hotspot Mutations

Mutation functional classification

• Innate immune system (Reactome: R-HSA-168249)

• Neutrophil degranulation (Reactome: R-HSA-6798695)

• Toll-like receptor signaling (KEGG: hsa04620)

BPI is a 456-amino-acid protein with two domains: an N-terminal domain (residues 1-200) that binds LPS and mediates bactericidal activity, and a C-terminal domain (residues 201-456) that facilitates opsonization and membrane interaction. It is structurally related to lipopolysaccharide-binding protein (LBP) and belongs to the BPI/LBP/PLUNC family. BPI is synthesized as a preproprotein and stored in neutrophil granules. Upon release, it binds to the lipid A moiety of LPS, disrupting the outer membrane of Gram-negative bacteria and neutralizing endotoxin. Recombinant BPI (rBPI21) has been investigated as a therapeutic agent for sepsis and other inflammatory conditions.