BPIFA1

This gene is the human homolog of murine plunc, and like the mouse gene, is specifically expressed in the upper airways and nasopharyngeal regions. The encoded antimicrobial protein displays antibacterial activity against Gram-negative bacteria. It is thought to be involved in inflammatory responses to irritants in the upper airways and may also serve as a potential molecular marker for detection of micrometastasis in non-small-cell lung cancer. Multiple transcript variants resulting from alternative splicing in the 3' UTR have been detected, but the full-length nature of only three are known.

Full Name

Bpi Fold Containing Family A Member 1

Function

Lipid-binding protein which shows high specificity for the surfactant phospholipid dipalmitoylphosphatidylcholine (DPPC) (PubMed:25223608).
Plays a role in the innate immune responses of the upper airways (PubMed:23499554, PubMed:23132494).
Reduces the surface tension in secretions from airway epithelia and inhibits the formation of biofilm by pathogenic Gram-negative bacteria, such as P.aeruginosa and K.pneumoniae (PubMed:23499554, PubMed:23132494, PubMed:27145151).
Negatively regulates proteolytic cleavage of SCNN1G, an event that is required for activation of the epithelial sodium channel (ENaC), and thereby contributes to airway surface liquid homeostasis and proper clearance of mucus (PubMed:24124190, PubMed:24043776).
Plays a role in the airway inflammatory response after exposure to irritants (PubMed:11425234).
May attract macrophages and neutrophils (PubMed:23132494).

Biological Process

Antibacterial humoral response Source: UniProtKB
Antimicrobial humoral immune response mediated by antimicrobial peptide Source: UniProtKB
Antimicrobial humoral response Source: Reactome
Defense response to virus Source: UniProtKB
Immune response in nasopharyngeal-associated lymphoid tissue Source: UniProtKB
Innate immune response Source: UniProtKB
Multicellular organismal water homeostasis Source: UniProtKB
Negative regulation of single-species biofilm formation in or on host organism Source: UniProtKB
Regulation of liquid surface tension Source: UniProtKB
Regulation of sodium ion transmembrane transport Source: UniProtKB

Cellular Location

Secreted. Apical side of airway epithelial cells. Detected in airway surface liquid, nasal mucus and sputum.

PTM

May be N-glycosylated.