ID PSPB_HUMAN Reviewed; 381 AA. AC P07988; Q96R04; DT 01-AUG-1988, integrated into UniProtKB/Swiss-Prot. DT 01-MAY-1992, sequence version 3. DT 27-MAR-2024, entry version 227. DE RecName: Full=Pulmonary surfactant-associated protein B; DE Short=SP-B; DE AltName: Full=18 kDa pulmonary-surfactant protein; DE AltName: Full=6 kDa protein; DE AltName: Full=Pulmonary surfactant-associated proteolipid SPL(Phe); DE Flags: Precursor; GN Name=SFTPB; Synonyms=SFTP3; OS Homo sapiens (Human). OC Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia; OC Eutheria; Euarchontoglires; Primates; Haplorrhini; Catarrhini; Hominidae; OC Homo. OX NCBI_TaxID=9606; RN [1] RP NUCLEOTIDE SEQUENCE [MRNA], AND PROTEIN SEQUENCE OF 201-214. RC TISSUE=Lung; RX PubMed=3597440; DOI=10.1016/s0021-9258(18)48005-2; RA Jacobs K.A., Phelps D.S., Steinbrink R., Fisch J., Kriz R., Mitsock L., RA Dougherty J.P., Taeusch H.W., Floros J.; RT "Isolation of a cDNA clone encoding a high molecular weight precursor to a RT 6-kDa pulmonary surfactant-associated protein."; RL J. Biol. Chem. 262:9808-9811(1987). RN [2] RP NUCLEOTIDE SEQUENCE [GENOMIC DNA], AND VARIANT ARG-228. RX PubMed=2924687; DOI=10.1089/dna.1.1989.8.75; RA Pilot-Matias T.J., Kister S.E., Fox J.L., Kropp K., Glasser S.W., RA Whitsett J.A.; RT "Structure and organization of the gene encoding human pulmonary surfactant RT proteolipid SP-B."; RL DNA 8:75-86(1989). RN [3] RP NUCLEOTIDE SEQUENCE [GENOMIC DNA], AND VARIANTS ILE-131; PHE-176 AND RP HIS-272. RG SeattleSNPs variation discovery resource; RL Submitted (JUL-2001) to the EMBL/GenBank/DDBJ databases. RN [4] RP NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA]. RC TISSUE=Brain; RX PubMed=15489334; DOI=10.1101/gr.2596504; RG The MGC Project Team; RT "The status, quality, and expansion of the NIH full-length cDNA project: RT the Mammalian Gene Collection (MGC)."; RL Genome Res. 14:2121-2127(2004). RN [5] RP NUCLEOTIDE SEQUENCE [MRNA] OF 99-381, AND VARIANT ARG-228. RX PubMed=3035561; DOI=10.1073/pnas.84.12.4007; RA Glasser S.W., Korfhagen T.R., Weaver T., Pilot-Matias T., Fox J.L., RA Whitsett J.A.; RT "cDNA and deduced amino acid sequence of human pulmonary surfactant- RT associated proteolipid SPL(Phe)."; RL Proc. Natl. Acad. Sci. U.S.A. 84:4007-4011(1987). RN [6] RP NUCLEOTIDE SEQUENCE [MRNA] OF 139-381. RX PubMed=3343343; DOI=10.1172/jci113391; RA Revak S.D., Merritt T.A., Degryse E., Stefani L., Courtney M., Hallman M., RA Cochrane C.G.; RT "Use of human surfactant low molecular weight apoproteins in the RT reconstitution of surfactant biologic activity."; RL J. Clin. Invest. 81:826-833(1988). RN [7] RP PROTEIN SEQUENCE OF 201-279, DISULFIDE BONDS, AND VARIANT ILE-228. RX PubMed=1568474; DOI=10.1016/0014-5793(92)81239-i; RA Johansson J., Joernvall H., Curstedt T.; RT "Human surfactant polypeptide SP-B. Disulfide bridges, C-terminal end, and RT peptide analysis of the airway form."; RL FEBS Lett. 301:165-167(1992). RN [8] RP STRUCTURE BY FTIR OF 201-225. RX PubMed=10798379; DOI=10.1034/j.1399-3011.2000.00693.x; RA Gordon L.M., Lee K.Y., Lipp M.M., Zasadzinski J.A., Walther F.J., RA Sherman M.A., Waring A.J.; RT "Conformational mapping of the N-terminal segment of surfactant protein B RT in lipid using 13C-enhanced Fourier transform infrared spectroscopy."; RL J. Pept. Res. 55:330-347(2000). RN [9] RP STRUCTURE BY NMR OF 208-278. RX PubMed=17845058; DOI=10.1021/bi7011756; RA Sarker M., Waring A.J., Walther F.J., Keough K.M., Booth V.; RT "Structure of mini-B, a functional fragment of surfactant protein B, in RT detergent micelles."; RL Biochemistry 46:11047-11056(2007). RN [10] RP VARIANT SMDP1 CYS-236. RX PubMed=7491219; RA Ballard P.L., Nogee L.M., Beers M.F., Ballard R.A., Planer B.C., Polk L., RA deMello D.E., Moxley M.A., Longmore W.J.; RT "Partial deficiency of surfactant protein B in an infant with chronic lung RT disease."; RL Pediatrics 96:1046-1052(1995). RN [11] RP VARIANT ILE-131. RX PubMed=11076040; DOI=10.1034/j.1399-0004.2000.580305.x; RA Lin Z., Pearson C., Chinchilli V., Pietschmann S.M., Luo J., Pison U., RA Floros J.; RT "Polymorphisms of human SP-A, SP-B, and SP-D genes: association of SP-B RT Thr131Ile with ARDS."; RL Clin. Genet. 58:181-191(2000). RN [12] RP INVOLVEMENT IN SUSCEPTIBILITY TO RDS. RX PubMed=11063734; DOI=10.1093/hmg/9.18.2751; RA Haataja R., Raemet M., Marttila R., Hallman M.; RT "Surfactant proteins A and B as interactive genetic determinants of RT neonatal respiratory distress syndrome."; RL Hum. Mol. Genet. 9:2751-2760(2000). 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:1568474}. CC -!- INTERACTION: CC P07988; Q6FHY5: MEOX2; NbExp=3; IntAct=EBI-14955352, EBI-16439278; CC -!- SUBCELLULAR LOCATION: Secreted, extracellular space, surface film. CC -!- DISEASE: Pulmonary surfactant metabolism dysfunction 1 (SMDP1) CC [MIM:265120]: A rare lung disorder due to impaired surfactant CC homeostasis. It is characterized by alveolar filling with floccular CC material that stains positive using the periodic acid-Schiff method and CC is derived from surfactant phospholipids and protein components. CC Excessive lipoproteins accumulation in the alveoli results in severe CC respiratory distress. {ECO:0000269|PubMed:7491219}. Note=The disease is CC caused by variants affecting the gene represented in this entry. CC -!- DISEASE: Respiratory distress syndrome in premature infants (RDS) CC [MIM:267450]: A lung disease affecting usually premature newborn CC infants. It is characterized by deficient gas exchange, diffuse CC atelectasis, high-permeability lung edema and fibrin-rich alveolar CC deposits called 'hyaline membranes'. {ECO:0000269|PubMed:11063734}. CC Note=Disease susceptibility may be associated with variants affecting CC the gene represented in this entry. A variation Ile to Thr at position CC 131 influences the association between specific alleles of SFTPA1 and CC respiratory distress syndrome in premature infants. 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). CC -!- SEQUENCE CAUTION: CC Sequence=AAA88099.1; Type=Erroneous initiation; Evidence={ECO:0000305}; CC -!- WEB RESOURCE: Name=SeattleSNPs; CC URL="http://pga.gs.washington.edu/data/sftpb/"; CC --------------------------------------------------------------------------- CC Copyrighted by the UniProt Consortium, see https://www.uniprot.org/terms CC Distributed under the Creative Commons Attribution (CC BY 4.0) License CC --------------------------------------------------------------------------- DR EMBL; J02761; AAA60212.1; -; mRNA. DR EMBL; M24461; AAB59541.1; -; Genomic_DNA. DR EMBL; AF400074; AAK77913.1; -; Genomic_DNA. DR EMBL; BC032785; AAH32785.1; -; mRNA. DR EMBL; M16764; AAA88099.1; ALT_INIT; mRNA. DR EMBL; M19097; AAA36628.1; -; mRNA. DR CCDS; CCDS1983.3; -. DR PIR; A31361; LNHUB. DR RefSeq; NP_000533.3; NM_000542.3. DR RefSeq; NP_942140.2; NM_198843.2. DR PDB; 1DFW; IR; -; A=201-225. DR PDB; 1KMR; NMR; -; A=211-225. DR PDB; 1RG3; NMR; -; A=263-278. DR PDB; 1RG4; NMR; -; A=263-278. DR PDB; 1SSZ; IR; -; A=208-278. DR PDB; 2DWF; NMR; -; A=208-278. DR PDB; 2JOU; NMR; -; A=208-278. DR PDB; 2M0H; NMR; -; A=259-280. DR PDB; 2M1T; NMR; -; A=259-278. DR PDBsum; 1DFW; -. DR PDBsum; 1KMR; -. DR PDBsum; 1RG3; -. DR PDBsum; 1RG4; -. DR PDBsum; 1SSZ; -. DR PDBsum; 2DWF; -. DR PDBsum; 2JOU; -. DR PDBsum; 2M0H; -. DR PDBsum; 2M1T; -. DR AlphaFoldDB; P07988; -. DR BMRB; P07988; -. DR PCDDB; P07988; -. DR SMR; P07988; -. DR BioGRID; 112337; 2. DR IntAct; P07988; 1. DR STRING; 9606.ENSP00000499683; -. DR GlyCosmos; P07988; 2 sites, No reported glycans. DR GlyGen; P07988; 2 sites. DR PhosphoSitePlus; P07988; -. DR SwissPalm; P07988; -. DR BioMuta; SFTPB; -. DR DMDM; 131418; -. DR MassIVE; P07988; -. DR PaxDb; 9606-ENSP00000386346; -. DR PeptideAtlas; P07988; -. DR ProteomicsDB; 52054; -. DR Antibodypedia; 31946; 396 antibodies from 31 providers. DR DNASU; 6439; -. DR Ensembl; ENST00000393822.7; ENSP00000377409.4; ENSG00000168878.19. DR Ensembl; ENST00000409383.6; ENSP00000386346.2; ENSG00000168878.19. DR Ensembl; ENST00000519937.7; ENSP00000428719.2; ENSG00000168878.19. DR GeneID; 6439; -. DR KEGG; hsa:6439; -. DR MANE-Select; ENST00000519937.7; ENSP00000428719.2; NM_000542.5; NP_000533.4. DR UCSC; uc061lja.1; human. DR AGR; HGNC:10801; -. DR CTD; 6439; -. DR DisGeNET; 6439; -. DR GeneCards; SFTPB; -. DR HGNC; HGNC:10801; SFTPB. DR HPA; ENSG00000168878; Tissue enriched (lung). DR MalaCards; SFTPB; -. DR MIM; 178640; gene. DR MIM; 265120; phenotype. DR MIM; 267450; phenotype. DR neXtProt; NX_P07988; -. DR OpenTargets; ENSG00000168878; -. DR Orphanet; 70587; Infant acute respiratory distress syndrome. DR Orphanet; 217563; Neonatal acute respiratory distress due to SP-B deficiency. DR PharmGKB; PA35713; -. DR VEuPathDB; HostDB:ENSG00000168878; -. DR eggNOG; KOG1340; Eukaryota. DR GeneTree; ENSGT00940000161711; -. DR InParanoid; P07988; -. DR OMA; PKFWCQS; -. DR OrthoDB; 7299at2759; -. DR PhylomeDB; P07988; -. DR PathwayCommons; P07988; -. DR Reactome; R-HSA-5683826; Surfactant metabolism. DR Reactome; R-HSA-5688031; Defective pro-SFTPB causes SMDP1 and RDS. DR Reactome; R-HSA-5688849; Defective CSF2RB causes SMDP5. DR Reactome; R-HSA-5688890; Defective CSF2RA causes SMDP4. DR SignaLink; P07988; -. DR SIGNOR; P07988; -. DR BioGRID-ORCS; 6439; 15 hits in 1143 CRISPR screens. DR ChiTaRS; SFTPB; human. DR EvolutionaryTrace; P07988; -. DR GeneWiki; Pulmonary_surfactant-associated_protein_B; -. DR GenomeRNAi; 6439; -. DR Pharos; P07988; Tbio. DR PRO; PR:P07988; -. DR Proteomes; UP000005640; Chromosome 2. DR RNAct; P07988; Protein. DR Bgee; ENSG00000168878; Expressed in lower lobe of lung and 176 other cell types or tissues. DR ExpressionAtlas; P07988; baseline and differential. DR GO; GO:0097208; C:alveolar lamellar body; IBA:GO_Central. DR GO; GO:0045334; C:clathrin-coated endocytic vesicle; TAS:Reactome. DR GO; GO:0005789; C:endoplasmic reticulum membrane; TAS:Reactome. DR GO; GO:0005576; C:extracellular region; TAS:Reactome. DR GO; GO:0042599; C:lamellar body; TAS:Reactome. DR GO; GO:0005764; C:lysosome; IEA:InterPro. DR GO; GO:0005771; C:multivesicular body; IBA:GO_Central. DR GO; GO:0097486; C:multivesicular body lumen; TAS:Reactome. DR GO; GO:0009887; P:animal organ morphogenesis; TAS:ProtInc. DR GO; GO:0007585; P:respiratory gaseous exchange by respiratory system; TAS:ProtInc. DR GO; GO:0006665; P:sphingolipid metabolic process; IEA:InterPro. DR Gene3D; 1.10.225.10; Saposin-like; 2. DR InterPro; IPR003119; SAP_A. DR InterPro; IPR007856; SapB_1. DR InterPro; IPR008138; SapB_2. DR InterPro; IPR008373; Saposin. DR InterPro; IPR011001; Saposin-like. DR InterPro; IPR008139; SaposinB_dom. DR PANTHER; PTHR11480:SF33; PULMONARY SURFACTANT-ASSOCIATED PROTEIN B; 1. DR PANTHER; PTHR11480; SAPOSIN-RELATED; 1. DR Pfam; PF02199; SapA; 1. DR Pfam; PF05184; SapB_1; 1. DR Pfam; PF03489; SapB_2; 2. DR PRINTS; PR01797; SAPOSIN. DR SMART; SM00162; SAPA; 1. DR SMART; SM00741; SapB; 3. DR SUPFAM; SSF47862; Saposin; 3. DR PROSITE; PS51110; SAP_A; 1. DR PROSITE; PS50015; SAP_B; 3. DR Genevisible; P07988; HS. PE 1: Evidence at protein level; KW 3D-structure; Direct protein sequencing; Disease variant; Disulfide bond; KW Gaseous exchange; Glycoprotein; Reference proteome; Repeat; Secreted; KW Signal; Surface film. FT SIGNAL 1..24 FT /evidence="ECO:0000255" FT PROPEP 25..200 FT /id="PRO_0000031647" FT CHAIN 201..279 FT /note="Pulmonary surfactant-associated protein B" FT /id="PRO_0000031648" FT PROPEP 280..381 FT /id="PRO_0000031649" FT DOMAIN 25..65 FT /note="Saposin A-type" FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00414" FT DOMAIN 65..147 FT /note="Saposin B-type 1" FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00415" FT DOMAIN 204..281 FT /note="Saposin B-type 2" FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00415" FT DOMAIN 295..370 FT /note="Saposin B-type 3" FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00415" FT CARBOHYD 129 FT /note="N-linked (GlcNAc...) asparagine" FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00415" FT CARBOHYD 311 FT /note="N-linked (GlcNAc...) asparagine" FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00415" FT DISULFID 69..143 FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00415" FT DISULFID 72..137 FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00415" FT DISULFID 100..112 FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00415" FT DISULFID 208..277 FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00415, FT ECO:0000269|PubMed:1568474" FT DISULFID 211..271 FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00415, FT ECO:0000269|PubMed:1568474" FT DISULFID 235..246 FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00415, FT ECO:0000269|PubMed:1568474" FT DISULFID 248 FT /note="Interchain" FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00415, FT ECO:0000269|PubMed:1568474" FT DISULFID 299..366 FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00415" FT DISULFID 302..360 FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00415" FT DISULFID 325..335 FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00415" FT VARIANT 131 FT /note="T -> I (in dbSNP:rs1130866)" FT /evidence="ECO:0000269|PubMed:11076040, ECO:0000269|Ref.3" FT /id="VAR_006948" FT VARIANT 176 FT /note="L -> F (in dbSNP:rs3024801)" FT /evidence="ECO:0000269|Ref.3" FT /id="VAR_013099" FT VARIANT 228 FT /note="A -> I (requires 2 nucleotide substitutions)" FT /evidence="ECO:0000269|PubMed:1568474" FT /id="VAR_006950" FT VARIANT 228 FT /note="A -> R (requires 2 nucleotide substitutions)" FT /evidence="ECO:0000269|PubMed:2924687, FT ECO:0000269|PubMed:3035561" FT /id="VAR_006949" FT VARIANT 236 FT /note="R -> C (in SMDP1; dbSNP:rs137853202)" FT /evidence="ECO:0000269|PubMed:7491219" FT /id="VAR_036856" FT VARIANT 272 FT /note="R -> H (in dbSNP:rs3024809)" FT /evidence="ECO:0000269|Ref.3" FT /id="VAR_013100" FT CONFLICT 178 FT /note="L -> V (in Ref. 6; AAA36628)" FT /evidence="ECO:0000305" FT CONFLICT 318 FT /note="P -> L (in Ref. 5; AAA88099)" FT /evidence="ECO:0000305" FT HELIX 213..221 FT /evidence="ECO:0007829|PDB:1KMR" FT HELIX 260..263 FT /evidence="ECO:0007829|PDB:2M0H" FT STRAND 265..268 FT /evidence="ECO:0007829|PDB:1RG3" FT HELIX 269..276 FT /evidence="ECO:0007829|PDB:1RG3" SQ SEQUENCE 381 AA; 42117 MW; 9FD7F66678A35153 CRC64; MAESHLLQWL LLLLPTLCGP GTAAWTTSSL ACAQGPEFWC QSLEQALQCR ALGHCLQEVW GHVGADDLCQ ECEDIVHILN KMAKEAIFQD TMRKFLEQEC NVLPLKLLMP QCNQVLDDYF PLVIDYFQNQ TDSNGICMHL GLCKSRQPEP EQEPGMSDPL PKPLRDPLPD PLLDKLVLPV LPGALQARPG PHTQDLSEQQ FPIPLPYCWL CRALIKRIQA MIPKGALAVA VAQVCRVVPL VAGGICQCLA ERYSVILLDT LLGRMLPQLV CRLVLRCSMD DSAGPRSPTG EWLPRDSECH LCMSVTTQAG NSSEQAIPQA MLQACVGSWL DREKCKQFVE QHTPQLLTLV PRGWDAHTTC QALGVCGTMS SPLQCIHSPD L //