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pulmonary surfactant-associated protein B; SP-B; 18 kD pulmonary-surfactant protein; 6 kD protein; pulmonary surfactant-associated proteolipid SPL(Phe) (SFTPB, SFTP3)
Function:
- Pulmonary surfactant-associated proteins promote alveolar stability by lowering the surface tension at the air-liquid interface in the peripheral air spaces
- SP-B increases the collapse pressure of palmitic acid to nearly 70 millinewtons per meter
Structure:
- homodimer; disulfide-linked
- contains 1 saposin A-type domain
- contains 3 saposin B-type domains
Compartment:
- secreted, extracellular space, surface film
Pathology:
- defects in SFTPB are the cause of pulmonary surfactant metabolism dysfunction type 1 (pulmonary alveolar proteinosis due to surfactant protein B)
- genetic variations in SFTPB are a cause of susceptibility to neonatal respiratory distress syndrome
- a variation Ile to Thr at position 131 influences the association between specific alleles of SFTPA1 & neonatal RDS
General
glycoprotein
proteolipid
secreted protein
Properties
SIZE: entity length = 381 aa
MW = 42 kD
COMPARTMENT: extracellular compartment
MOTIF: signal sequence {1-24}
Saposin A-type {25-65}
Saposin B-type 1 {65-147}
MOTIF: cysteine residue {C69}
MODIFICATION: cysteine residue {C143}
cysteine residue {C72}
MODIFICATION: cysteine residue {C137}
cysteine residue {C100}
MODIFICATION: cysteine residue {C112}
cysteine residue {C112}
MODIFICATION: cysteine residue {C100}
N-glycosylation site {N129}
cysteine residue {C137}
MODIFICATION: cysteine residue {C72}
cysteine residue {C143}
MODIFICATION: cysteine residue {C69}
Saposin B-type 2 {204-281}
MOTIF: cysteine residue {C208}
MODIFICATION: cysteine residue {C277}
cysteine residue {C211}
MODIFICATION: cysteine residue {C271}
cysteine residue {C235}
MODIFICATION: cysteine residue {C246}
cysteine residue {C246}
MODIFICATION: cysteine residue {C235}
cysteine residue {C248}
MODIFICATION: cysteine residue {CINTERCHAIN}
cysteine residue {C271}
MODIFICATION: cysteine residue {C211}
cysteine residue {C277}
MODIFICATION: cysteine residue {C208}
Saposin B-type 3 {295-370}
MOTIF: cysteine residue {C299}
MODIFICATION: cysteine residue {C366}
cysteine residue {C302}
MODIFICATION: cysteine residue {C360}
N-glycosylation site {N311}
cysteine residue {C325}
MODIFICATION: cysteine residue {C335}
cysteine residue {C335}
MODIFICATION: cysteine residue {C325}
cysteine residue {C360}
MODIFICATION: cysteine residue {C302}
cysteine residue {C366}
MODIFICATION: cysteine residue {C299}
Database Correlations
OMIM correlations
UniProt P07988
PFAM correlations
Entrez Gene 6439
Kegg hsa:6439
References
- UniProt :accession P07988
- GeneReviews
http://www.ncbi.nlm.nih.gov/sites/genetests/lab/gene/SFTPB
- SeattleSNPs
http://pga.gs.washington.edu/data/sftpb/