P15285 (PSPB_RABIT) Reviewed, UniProtKB/Swiss-Prot

Names and origin

Protein names

Recommended name:
Pulmonary surfactant-associated protein B
Short name=SP-B

Alternative name(s):
6 kDa protein
Pulmonary surfactant-associated proteolipid SPL(Phe)

Gene names

Name:	SFTPB
Synonyms:	SFTP3

Organism

Oryctolagus cuniculus (Rabbit) [Reference proteome]

Taxonomic identifier

9986 [NCBI]

Taxonomic lineage

cellular organisms › Eukaryota › Opisthokonta › Metazoa › Eumetazoa › Bilateria › Deuterostomia › Chordata › Craniata › Vertebrata › Gnathostomata › Teleostomi › Euteleostomi › Sarcopterygii › Tetrapoda › Amniota › Mammalia › Theria › Eutheria › Euarchontoglires › Glires › Lagomorpha › Leporidae › Oryctolagus

Protein attributes

Sequence length	370 AA.
Sequence status	Complete.
Sequence processing	The displayed sequence is further processed into a mature form.
Protein existence	Evidence at transcript level

General annotation (Comments)

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.
Subunit structure	Homodimer; disulfide-linked.
Subcellular location	Secreted › extracellular space › surface film.
Miscellaneous	Pulmonary surfactant consists of 90% lipid and 10% protein. There are 4 surfactant-associated proteins: 2 collagenous, carbohydrate-binding glycoproteins (SP-A and SP-D) and 2 small hydrophobic proteins (SP-B and SP-C).
Sequence similarities	Contains 1 saposin A-type domain. Contains 3 saposin B-type domains.

Ontologies

Keywords
Biological process	Gaseous exchange
Cellular component	Secreted Surface film
Domain	Repeat Signal
PTM	Disulfide bond Glycoprotein
Technical term	Complete proteome Reference proteome
Gene Ontology (GO)
Biological_process	lipid metabolic process Inferred from electronic annotation. Source: InterPro respiratory gaseous exchange Inferred from electronic annotation. Source: UniProtKB-KW
Cellular_component	cytoplasm Inferred from electronic annotation. Source: Compara extracellular space Inferred from electronic annotation. Source: UniProtKB-SubCell
Complete GO annotation...

Sequence annotation (Features)

	Feature key	Position(s)	Length	Description	Graphical view	Feature identifier
Molecule processing
	Signal peptide	1 – 24	24	Potential
	Propeptide	25 – 184	160			PRO_0000031653
	Chain	185 – 263	79	Pulmonary surfactant-associated protein B		PRO_0000031654
	Propeptide	264 – 370	107			PRO_0000031655
Regions
	Domain	26 – 66	41	Saposin A-type
	Domain	66 – 148	83	Saposin B-type 1
	Domain	188 – 265	78	Saposin B-type 2
	Domain	284 – 359	76	Saposin B-type 3
Amino acid modifications
	Glycosylation	300	1	N-linked (GlcNAc...) Potential
	Disulfide bond	70 ↔ 144		By similarity
	Disulfide bond	73 ↔ 138		By similarity
	Disulfide bond	101 ↔ 113		By similarity
	Disulfide bond	192 ↔ 261		By similarity
	Disulfide bond	195 ↔ 255		By similarity
	Disulfide bond	219 ↔ 230		By similarity
	Disulfide bond	232		Interchain By similarity
	Disulfide bond	288 ↔ 355		By similarity
	Disulfide bond	291 ↔ 349		By similarity
	Disulfide bond	314 ↔ 324		By similarity
Experimental info
	Sequence conflict	15	1	Missing in AAA67934. Ref.2
	Sequence conflict	129	1	Q → L in AAB48076. Ref.3
	Sequence conflict	184	1	R → P in AAA31466. Ref.1
	Sequence conflict	232	1	C → R in AAA67934. Ref.2
	Sequence conflict	289	1	R → P in AAB48076. Ref.3
	Sequence conflict	329 – 355	27	ELHTP…ALGAC → AAHAPAAEPAVQGLGCPRNL PGPEGRV in AAA31466. Ref.1

Sequences

	Sequence		Length	Mass (Da)
	P15285 [UniParc]. Last modified October 1, 1996. Version 2. Checksum: 423047A69B12DCB5	FASTA	370	40,610
	10 20 30 40 50 60 MAKSHLPPWL LLLLLPTLCG PGTAVWATSP LACAQGPEFW CQSLEQALQC KALGHCLQEV 70 80 90 100 110 120 WGHVGADDLC QECQDIVNIL TKMTKEAIFQ DTIRKFLEHE CDVLPLKLLV PQCHHVLDVY 130 140 150 160 170 180 FPLTITYFQS QINAKAICQH LGLCQPGSPE PPLDPLPDKL VLPTLLGALP AKPGPHTQDL 190 200 210 220 230 240 SAQRFPIPLP LCWLCRTLLK RIQAMIPKGV LAMAVAQVCH VVPLVVGGIC QCLAERYTVI 250 260 270 280 290 300 LLEVLLGHVL PQLVCGLVLR CSSVDSIGQV PPTLEALPGE WLPQDPECRL CMSVTTQARN 310 320 330 340 350 360 ISEQTRPQAV YHACLSSQLD KQECEQFVEL HTPQLLSLLS RGWDARAICQ ALGACVATLS 370 PLQCIQSPHF

References

[1]	"Isolation and characterization of the cDNA for pulmonary surfactant-associated protein-B (SP-B) in the rabbit." Xu J., Richardson C., Ford C., Spencer T., Li-Juan Y., Mackie G., Hammond G., Possmayer F. Biochem. Biophys. Res. Commun. 160:325-332(1989) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [MRNA]. Tissue: Lung.
[2]	"Transcription and mRNA stability regulate developmental and hormonal expression of rabbit surfactant protein B gene." Margana R.K., Boggaram V. Am. J. Physiol. 268:L481-L490(1995) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [MRNA]. Strain: New Zealand white.
[3]	"Rabbit surfactant protein B gene: structure and functional characterization of the promoter." Margana R.K., Boggaram V. Am. J. Physiol. 270:L601-L612(1996) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA]. Tissue: Liver.
[4]	"The upstream region of the SP-B gene: intrinsic promoter activity and glucocorticoid responsiveness related to a new DNA-binding protein." Luzi P., Anceschi M., Strayer D.S. Gene 165:285-290(1995) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA] OF 1-34.

Cross-references

Sequence databases
EMBL GenBank DDBJ	M24901 mRNA. Translation: AAA31466.1. U17106 mRNA. Translation: AAA67934.1. U40853 Genomic DNA. Translation: AAB48076.1. S80649 Genomic DNA. Translation: AAD14335.1.
PIR	LNRBB. A32421. I46531.
RefSeq	NP_001075812.1. NM_001082343.1.
UniGene	Ocu.1963.
3D structure databases
ProteinModelPortal	P15285.
ModBase	Search...
Protein-protein interaction databases
STRING	9986.ENSOCUP00000025658.
Protocols and materials databases
StructuralBiologyKnowledgebase	Search...
Genome annotation databases
Ensembl	ENSOCUT00000021287; ENSOCUP00000025658; ENSOCUG00000020733.
GeneID	100009194.
Organism-specific databases
CTD	100009194.
Phylogenomic databases
eggNOG	NOG286450.
GeneTree	ENSGT00530000063434.
HOGENOM	HOG000115745.
HOVERGEN	HBG006905.
OMA	CWLCRTL.
Family and domain databases
Gene3D	1.10.225.10. 3 hits.
InterPro	IPR003119. SapA. IPR007856. SapB_1. IPR008138. SapB_2. IPR011001. Saposin-like. IPR008139. SaposinB. [Graphical view]
Pfam	PF02199. SapA. 1 hit. PF05184. SapB_1. 1 hit. PF03489. SapB_2. 2 hits. [Graphical view]
SMART	SM00162. SAPA. 1 hit. SM00741. SapB. 3 hits. [Graphical view]
SUPFAM	SSF47862. Saposin_like. 3 hits.
PROSITE	PS51110. SAP_A. 1 hit. PS50015. SAP_B. 3 hits. [Graphical view]
ProtoNet	Search...

Entry information

Entry name

PSPB_RABIT

Accession

Primary (citable) accession number: P15285
Secondary accession number(s): P79333

Entry history

Integrated into UniProtKB/Swiss-Prot:	April 1, 1990
Last sequence update:	October 1, 1996
Last modified:	April 3, 2013
This is version 103 of the entry and version 2 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation program

Chordata Protein Annotation Program