ID   BPIA1_PIG               Reviewed;         249 AA.
AC   Q5XW65; Q5XW64;
DT   05-JUL-2005, integrated into UniProtKB/Swiss-Prot.
DT   23-NOV-2004, sequence version 1.
DT   25-MAY-2022, entry version 70.
DE   RecName: Full=BPI fold-containing family A member 1;
DE   AltName: Full=Lung and nasal epithelium carcinoma-associated protein;
DE   AltName: Full=Palate lung and nasal epithelium clone protein;
DE   Flags: Precursor;
GN   Name=BPIFA1; Synonyms=PLUNC, SPLUNC1;
OS   Sus scrofa (Pig).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia;
OC   Eutheria; Laurasiatheria; Artiodactyla; Suina; Suidae; Sus.
OX   NCBI_TaxID=9823;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA / MRNA], AND TISSUE SPECIFICITY.
RC   TISSUE=Lung;
RX   PubMed=15777615; DOI=10.1016/j.bbaexp.2005.01.005;
RA   Larsen K., Madsen L.B., Bendixen C.;
RT   "Porcine SPLUNC1: molecular cloning, characterization and expression
RT   analysis.";
RL   Biochim. Biophys. Acta 1727:220-226(2005).
CC   -!- FUNCTION: Lipid-binding protein which shows high specificity for the
CC       surfactant phospholipid dipalmitoylphosphatidylcholine (DPPC). Plays a
CC       role in the innate immune responses of the upper airways. Reduces the
CC       surface tension in secretions from airway epithelia and inhibits the
CC       formation of biofilm by pathogenic Gram-negative bacteria, such as
CC       P.aeruginosa and K.pneumoniae. Negatively regulates proteolytic
CC       cleavage of SCNN1G, an event that is required for activation of the
CC       epithelial sodium channel (ENaC), and thereby contributes to airway
CC       surface liquid homeostasis and proper clearance of mucus. Plays a role
CC       in the airway inflammatory response after exposure to irritants. May
CC       attract macrophages and neutrophils. {ECO:0000250|UniProtKB:Q9NP55}.
CC   -!- SUBUNIT: Monomer. Interacts (via N-terminus) with SCNN1B, a subunit of
CC       the heterotrimeric epithelial sodium channel (ENaC); this inhibits
CC       proteolytic activation of ENaC (By similarity). {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000250}. Note=Apical side of
CC       airway epithelial cells. Detected in airway surface liquid, nasal mucus
CC       and sputum (By similarity). {ECO:0000250}.
CC   -!- TISSUE SPECIFICITY: Expressed in lung and trachea.
CC       {ECO:0000269|PubMed:15777615}.
CC   -!- SIMILARITY: Belongs to the BPI/LBP/Plunc superfamily. Plunc family.
CC       {ECO:0000305}.
CC   -!- CAUTION: Reported to bind to bacterial lipopolysaccharide (LPS) in
CC       vitro. However, the in vivo significance of this is uncertain since
CC       other studies indicate little or no specificity for LPS.
CC       {ECO:0000250|UniProtKB:Q9NP55}.
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DR   EMBL; AY733063; AAU43633.1; -; mRNA.
DR   EMBL; AY733064; AAU43634.1; -; Genomic_DNA.
DR   RefSeq; NP_001005727.1; NM_001005727.1.
DR   AlphaFoldDB; Q5XW65; -.
DR   SMR; Q5XW65; -.
DR   STRING; 9823.ENSSSCP00000007731; -.
DR   PaxDb; Q5XW65; -.
DR   GeneID; 449524; -.
DR   KEGG; ssc:449524; -.
DR   CTD; 51297; -.
DR   eggNOG; ENOG502SR58; Eukaryota.
DR   InParanoid; Q5XW65; -.
DR   OrthoDB; 1275829at2759; -.
DR   Proteomes; UP000008227; Unplaced.
DR   Proteomes; UP000314985; Unplaced.
DR   GO; GO:0005615; C:extracellular space; ISS:UniProtKB.
DR   GO; GO:0008289; F:lipid binding; IEA:UniProtKB-KW.
DR   GO; GO:0019731; P:antibacterial humoral response; ISS:UniProtKB.
DR   GO; GO:0045087; P:innate immune response; ISS:UniProtKB.
DR   GO; GO:0050891; P:multicellular organismal water homeostasis; ISS:UniProtKB.
DR   GO; GO:1900229; P:negative regulation of single-species biofilm formation in or on host organism; ISS:UniProtKB.
DR   GO; GO:0050828; P:regulation of liquid surface tension; ISS:UniProtKB.
DR   GO; GO:1902305; P:regulation of sodium ion transmembrane transport; ISS:UniProtKB.
DR   InterPro; IPR017943; Bactericidal_perm-incr_a/b_dom.
DR   InterPro; IPR034307; BPIFA1.
DR   InterPro; IPR017942; Lipid-bd_serum_glycop_N.
DR   PANTHER; PTHR47015:SF1; PTHR47015:SF1; 1.
DR   Pfam; PF01273; LBP_BPI_CETP; 1.
DR   SUPFAM; SSF55394; SSF55394; 1.
PE   2: Evidence at transcript level;
KW   Antibiotic; Antimicrobial; Disulfide bond; Glycoprotein; Immunity;
KW   Innate immunity; Lipid-binding; Reference proteome; Secreted; Signal.
FT   SIGNAL          1..15
FT                   /evidence="ECO:0000255"
FT   CHAIN           16..249
FT                   /note="BPI fold-containing family A member 1"
FT                   /id="PRO_0000017177"
FT   REGION          81..86
FT                   /note="Important for surfactant activity and antibacterial
FT                   properties"
FT                   /evidence="ECO:0000250|UniProtKB:Q9NP55"
FT   CARBOHYD        151
FT                   /note="N-linked (GlcNAc...) asparagine"
FT                   /evidence="ECO:0000255"
FT   DISULFID        173..217
FT                   /evidence="ECO:0000250|UniProtKB:Q9NP55"
SQ   SEQUENCE   249 AA;  25829 MW;  5E3085F1994ACF06 CRC64;
     MFQVAGLIVF CGLLAQTTAL LEALPLGKAL PLALDQSPTD LVGSLTSTLS NGLLSEGVLG
     ILGNLPLLDI LKAGGNTPSG LLGGLLGKLS STIPLLNDIV DLQITDPQLL ELGLVQSPDG
     HRLYVTIPLS LVLNVKTSVV GSLLKLAVKL NITVELLAVK DEQGKSHLVL GDCTHSPGSL
     KISLLDGLGP LVPQDLLDSI TGVLDNVLPG LVQGEVCPLV NEVLSHLDVT LVHSIVDALI
     QGQEFVIKV