PSPB_PIG
ID PSPB_PIG Reviewed; 79 AA.
AC P15782;
DT 01-APR-1990, integrated into UniProtKB/Swiss-Prot.
DT 01-APR-1990, sequence version 1.
DT 25-MAY-2022, entry version 105.
DE RecName: Full=Pulmonary surfactant-associated protein B;
DE Short=SP-B;
DE AltName: Full=8 kDa protein;
DE AltName: Full=Pulmonary surfactant-associated proteolipid SPL(Phe);
GN Name=SFTPB; Synonyms=SFTP3;
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 PROTEIN SEQUENCE.
RX PubMed=3350011; DOI=10.1111/j.1432-1033.1988.tb13918.x;
RA Curstedt T., Johansson J., Barros-Soederling J., Robertson B., Nilsson G.,
RA Westberg M., Joernvall H.;
RT "Low-molecular-mass surfactant protein type 1. The primary structure of a
RT hydrophobic 8-kDa polypeptide with eight half-cystine residues.";
RL Eur. J. Biochem. 172:521-525(1988).
RN [2]
RP DISULFIDE BONDS.
RX PubMed=1648964; DOI=10.1021/bi00242a015;
RA Johansson J., Curstedt T., Joernvall H.;
RT "Surfactant protein B: disulfide bridges, structural properties, and
RT kringle similarities.";
RL Biochemistry 30:6917-6921(1991).
CC -!- FUNCTION: Pulmonary surfactant-associated proteins promote alveolar
CC stability by lowering the surface tension at the air-liquid interface
CC in the peripheral air spaces. SP-B increases the collapse pressure of
CC palmitic acid to nearly 70 millinewtons per meter.
CC -!- SUBUNIT: Homodimer; disulfide-linked. {ECO:0000269|PubMed:1648964}.
CC -!- SUBCELLULAR LOCATION: Secreted, extracellular space, surface film.
CC -!- MISCELLANEOUS: Pulmonary surfactant consists of 90% lipid and 10%
CC protein. There are 4 surfactant-associated proteins: 2 collagenous,
CC carbohydrate-binding glycoproteins (SP-A and SP-D) and 2 small
CC hydrophobic proteins (SP-B and SP-C).
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DR PIR; S00363; LNPG1.
DR AlphaFoldDB; P15782; -.
DR SMR; P15782; -.
DR STRING; 9823.ENSSSCP00000008786; -.
DR PaxDb; P15782; -.
DR PeptideAtlas; P15782; -.
DR eggNOG; KOG1340; Eukaryota.
DR Proteomes; UP000008227; Unplaced.
DR Proteomes; UP000314985; Unplaced.
DR GO; GO:0097208; C:alveolar lamellar body; IBA:GO_Central.
DR GO; GO:0005615; C:extracellular space; IBA:GO_Central.
DR GO; GO:0005771; C:multivesicular body; IBA:GO_Central.
DR GO; GO:0007585; P:respiratory gaseous exchange by respiratory system; IEA:UniProtKB-KW.
DR InterPro; IPR011001; Saposin-like.
DR InterPro; IPR008139; SaposinB_dom.
DR SMART; SM00741; SapB; 1.
DR SUPFAM; SSF47862; SSF47862; 1.
DR PROSITE; PS50015; SAP_B; 1.
PE 1: Evidence at protein level;
KW Direct protein sequencing; Disulfide bond; Gaseous exchange;
KW Reference proteome; Secreted; Surface film.
FT CHAIN 1..79
FT /note="Pulmonary surfactant-associated protein B"
FT /id="PRO_0000175241"
FT DOMAIN 4..79
FT /note="Saposin B-type"
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00415"
FT DISULFID 8..77
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00415,
FT ECO:0000269|PubMed:1648964"
FT DISULFID 11..71
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00415,
FT ECO:0000269|PubMed:1648964"
FT DISULFID 35..46
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00415,
FT ECO:0000269|PubMed:1648964"
FT DISULFID 48
FT /note="Interchain"
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00415,
FT ECO:0000269|PubMed:1648964"
FT VARIANT 57
FT /note="C -> L"
SQ SEQUENCE 79 AA; 8714 MW; EA3692061144566D CRC64;
FPIPLPFCWL CRTLIKRIQA VVPKGVLLKA VAQVCHVVPL PVGGICQCLA ERYIVICLNM
LLDRTLPQLV CGLVLRCSS
