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Protein

Extracellular sulfatase Sulf-2

Gene

SULF2

Organism
Homo sapiens (Human)
Status
Reviewed-Annotation score: Annotation score: 5 out of 5-Experimental evidence at protein leveli

Functioni

Exhibits arylsulfatase activity and highly specific endoglucosamine-6-sulfatase activity. It can remove sulfate from the C-6 position of glucosamine within specific subregions of intact heparin.

Cofactori

Ca2+By similarityNote: Binds 1 Ca2+ ion per subunit.By similarity

pH dependencei

Optimum pH is 7.0-8.0.

Sites

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Metal bindingi52 – 521CalciumBy similarity
Metal bindingi53 – 531CalciumBy similarity
Metal bindingi88 – 881Calcium; via 3-oxoalanineBy similarity
Metal bindingi317 – 3171CalciumBy similarity
Metal bindingi318 – 3181CalciumBy similarity

GO - Molecular functioni

  • arylsulfatase activity Source: UniProtKB
  • calcium ion binding Source: InterPro
  • N-acetylglucosamine-6-sulfatase activity Source: UniProtKB

GO - Biological processi

Complete GO annotation...

Keywords - Molecular functioni

Hydrolase

Keywords - Ligandi

Calcium, Metal-binding

Names & Taxonomyi

Protein namesi
Recommended name:
Extracellular sulfatase Sulf-2 (EC:3.1.6.-)
Short name:
hSulf-2
Gene namesi
Name:SULF2
Synonyms:KIAA1247
ORF Names:UNQ559/PRO1120
OrganismiHomo sapiens (Human)
Taxonomic identifieri9606 [NCBI]
Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaEuarchontogliresPrimatesHaplorrhiniCatarrhiniHominidaeHomo
Proteomesi
  • UP000005640 Componenti: Chromosome 20

Organism-specific databases

HGNCiHGNC:20392. SULF2.

Subcellular locationi

GO - Cellular componenti

  • cell surface Source: UniProtKB
  • endoplasmic reticulum Source: UniProtKB
  • extracellular space Source: UniProtKB
  • Golgi stack Source: UniProtKB-SubCell
  • plasma membrane Source: UniProtKB
Complete GO annotation...

Keywords - Cellular componenti

Endoplasmic reticulum, Golgi apparatus

Pathology & Biotechi

Mutagenesis

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Mutagenesisi88 – 892CC → AA: Loss of arylsulfatase activity. 1 Publication

Organism-specific databases

PharmGKBiPA134902131.

Polymorphism and mutation databases

BioMutaiSULF2.
DMDMi33112446.

PTM / Processingi

Molecule processing

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Signal peptidei1 – 2424Sequence analysisAdd
BLAST
Chaini25 – 870846Extracellular sulfatase Sulf-2PRO_0000033440Add
BLAST

Amino acid modifications

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Glycosylationi65 – 651N-linked (GlcNAc...)Sequence analysis
Modified residuei88 – 8813-oxoalanine (Cys)By similarity
Glycosylationi112 – 1121N-linked (GlcNAc...)Sequence analysis
Glycosylationi132 – 1321N-linked (GlcNAc...)Sequence analysis
Glycosylationi149 – 1491N-linked (GlcNAc...)Sequence analysis
Glycosylationi171 – 1711N-linked (GlcNAc...)Sequence analysis
Glycosylationi198 – 1981N-linked (GlcNAc...)1 Publication
Glycosylationi241 – 2411N-linked (GlcNAc...)Sequence analysis
Glycosylationi561 – 5611N-linked (GlcNAc...)Sequence analysis
Glycosylationi608 – 6081N-linked (GlcNAc...)Sequence analysis
Glycosylationi717 – 7171N-linked (GlcNAc...)Sequence analysis
Glycosylationi754 – 7541N-linked (GlcNAc...)Sequence analysis
Glycosylationi764 – 7641N-linked (GlcNAc...)Sequence analysis

Post-translational modificationi

The conversion to 3-oxoalanine (also known as C-formylglycine, FGly), of a serine or cysteine residue in prokaryotes and of a cysteine residue in eukaryotes, is critical for catalytic activity.By similarity

Keywords - PTMi

Glycoprotein

Proteomic databases

MaxQBiQ8IWU5.
PaxDbiQ8IWU5.
PRIDEiQ8IWU5.
TopDownProteomicsiQ8IWU5-2. [Q8IWU5-2]

PTM databases

iPTMnetiQ8IWU5.
PhosphoSiteiQ8IWU5.

Expressioni

Tissue specificityi

Expressed at highest levels in the ovary, skeletal muscle, stomach, brain, uterus, heart, kidney and placenta.

Gene expression databases

BgeeiQ8IWU5.
CleanExiHS_SULF2.
ExpressionAtlasiQ8IWU5. baseline and differential.
GenevisibleiQ8IWU5. HS.

Organism-specific databases

HPAiHPA002325.

Interactioni

Protein-protein interaction databases

BioGridi121010. 17 interactions.
IntActiQ8IWU5. 2 interactions.
STRINGi9606.ENSP00000353007.

Structurei

3D structure databases

ProteinModelPortaliQ8IWU5.
SMRiQ8IWU5. Positions 35-395.
ModBaseiSearch...
MobiDBiSearch...

Family & Domainsi

Sequence similaritiesi

Belongs to the sulfatase family.Curated

Keywords - Domaini

Signal

Phylogenomic databases

eggNOGiKOG3731. Eukaryota.
COG3119. LUCA.
GeneTreeiENSGT00400000022041.
HOVERGENiHBG056431.
InParanoidiQ8IWU5.
KOiK14607.
OMAiGEACACD.
OrthoDBiEOG7FR7H6.
PhylomeDBiQ8IWU5.
TreeFamiTF313545.

Family and domain databases

Gene3Di3.40.720.10. 3 hits.
InterProiIPR017849. Alkaline_Pase-like_a/b/a.
IPR017850. Alkaline_phosphatase_core.
IPR014615. Extracellular_sulfatase.
IPR024609. Extracellular_sulfatase_C.
IPR024607. Sulfatase_CS.
IPR000917. Sulfatase_N.
[Graphical view]
PfamiPF12548. DUF3740. 1 hit.
PF00884. Sulfatase. 1 hit.
[Graphical view]
PIRSFiPIRSF036665. Sulf1. 1 hit.
SUPFAMiSSF53649. SSF53649. 3 hits.
PROSITEiPS00523. SULFATASE_1. 1 hit.
[Graphical view]

Sequences (2)i

Sequence statusi: Complete.

Sequence processingi: The displayed sequence is further processed into a mature form.

This entry describes 2 isoformsi produced by alternative splicing. AlignAdd to basket

Isoform 1 (identifier: Q8IWU5-1) [UniParc]FASTAAdd to basket

This isoform has been chosen as the 'canonical' sequence. All positional information in this entry refers to it. This is also the sequence that appears in the downloadable versions of the entry.

« Hide

        10         20         30         40         50
MGPPSLVLCL LSATVFSLLG GSSAFLSHHR LKGRFQRDRR NIRPNIILVL
60 70 80 90 100
TDDQDVELGS MQVMNKTRRI MEQGGAHFIN AFVTTPMCCP SRSSILTGKY
110 120 130 140 150
VHNHNTYTNN ENCSSPSWQA QHESRTFAVY LNSTGYRTAF FGKYLNEYNG
160 170 180 190 200
SYVPPGWKEW VGLLKNSRFY NYTLCRNGVK EKHGSDYSKD YLTDLITNDS
210 220 230 240 250
VSFFRTSKKM YPHRPVLMVI SHAAPHGPED SAPQYSRLFP NASQHITPSY
260 270 280 290 300
NYAPNPDKHW IMRYTGPMKP IHMEFTNMLQ RKRLQTLMSV DDSMETIYNM
310 320 330 340 350
LVETGELDNT YIVYTADHGY HIGQFGLVKG KSMPYEFDIR VPFYVRGPNV
360 370 380 390 400
EAGCLNPHIV LNIDLAPTIL DIAGLDIPAD MDGKSILKLL DTERPVNRFH
410 420 430 440 450
LKKKMRVWRD SFLVERGKLL HKRDNDKVDA QEENFLPKYQ RVKDLCQRAE
460 470 480 490 500
YQTACEQLGQ KWQCVEDATG KLKLHKCKGP MRLGGSRALS NLVPKYYGQG
510 520 530 540 550
SEACTCDSGD YKLSLAGRRK KLFKKKYKAS YVRSRSIRSV AIEVDGRVYH
560 570 580 590 600
VGLGDAAQPR NLTKRHWPGA PEDQDDKDGG DFSGTGGLPD YSAANPIKVT
610 620 630 640 650
HRCYILENDT VQCDLDLYKS LQAWKDHKLH IDHEIETLQN KIKNLREVRG
660 670 680 690 700
HLKKKRPEEC DCHKISYHTQ HKGRLKHRGS SLHPFRKGLQ EKDKVWLLRE
710 720 730 740 750
QKRKKKLRKL LKRLQNNDTC SMPGLTCFTH DNQHWQTAPF WTLGPFCACT
760 770 780 790 800
SANNNTYWCM RTINETHNFL FCEFATGFLE YFDLNTDPYQ LMNAVNTLDR
810 820 830 840 850
DVLNQLHVQL MELRSCKGYK QCNPRTRNMD LGLKDGGSYE QYRQFQRRKW
860 870
PEMKRPSSKS LGQLWEGWEG
Length:870
Mass (Da):100,455
Last modified:March 1, 2003 - v1
Checksum:i74B1069CE2774D73
GO
Isoform 2 (identifier: Q8IWU5-2) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     832-834: Missing.

Note: May be due to a competing acceptor splice site.
Show »
Length:867
Mass (Da):100,156
Checksum:i1030E3CDAEC92A31
GO

Sequence cautioni

The sequence AAH20962.1 differs from that shown. Reason: Erroneous initiation. Curated
The sequence BAA86561.2 differs from that shown. Reason: Erroneous initiation. Curated
The sequence CAB61349.1 differs from that shown. Reason: Erroneous initiation. Curated

Natural variant

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Natural varianti76 – 761A → T.1 Publication
Corresponds to variant rs56218501 [ dbSNP | Ensembl ].
VAR_061885
Natural varianti531 – 5311Y → H in a breast cancer sample; somatic mutation. 1 Publication
VAR_036494
Natural varianti573 – 5731D → N in a breast cancer sample; somatic mutation. 1 Publication
VAR_036495
Natural varianti674 – 6741R → H.
Corresponds to variant rs10048853 [ dbSNP | Ensembl ].
VAR_052518

Alternative sequence

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Alternative sequencei832 – 8343Missing in isoform 2. 1 PublicationVSP_013362

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
AY101176 mRNA. Translation: AAM76861.1.
AB033073 mRNA. Translation: BAA86561.2. Different initiation.
AY358461 mRNA. Translation: AAQ88826.1.
CR749319 mRNA. Translation: CAH18174.1.
AL354813, AL034418 Genomic DNA. Translation: CAI17943.1.
AL034418 Genomic DNA. Translation: CAC17694.1. Sequence problems.
AL034418, AL354813 Genomic DNA. Translation: CAI42143.1.
CH471077 Genomic DNA. Translation: EAW75690.1.
CH471077 Genomic DNA. Translation: EAW75693.1.
CH471077 Genomic DNA. Translation: EAW75694.1.
CH471077 Genomic DNA. Translation: EAW75695.1.
BC020962 mRNA. Translation: AAH20962.1. Different initiation.
BC110539 mRNA. Translation: AAI10540.1.
AL133001 mRNA. Translation: CAB61349.1. Different initiation.
CCDSiCCDS13408.1. [Q8IWU5-1]
CCDS13409.2. [Q8IWU5-2]
RefSeqiNP_001155313.1. NM_001161841.1. [Q8IWU5-1]
NP_061325.1. NM_018837.3. [Q8IWU5-1]
NP_940998.2. NM_198596.2. [Q8IWU5-2]
XP_005260515.1. XM_005260458.1. [Q8IWU5-1]
XP_006723893.1. XM_006723830.1. [Q8IWU5-1]
UniGeneiHs.162016.

Genome annotation databases

EnsembliENST00000359930; ENSP00000353007; ENSG00000196562. [Q8IWU5-1]
ENST00000467815; ENSP00000418442; ENSG00000196562. [Q8IWU5-2]
ENST00000484875; ENSP00000418290; ENSG00000196562. [Q8IWU5-1]
GeneIDi55959.
KEGGihsa:55959.
UCSCiuc002xto.4. human. [Q8IWU5-1]

Keywords - Coding sequence diversityi

Alternative splicing, Polymorphism

Cross-referencesi

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
AY101176 mRNA. Translation: AAM76861.1.
AB033073 mRNA. Translation: BAA86561.2. Different initiation.
AY358461 mRNA. Translation: AAQ88826.1.
CR749319 mRNA. Translation: CAH18174.1.
AL354813, AL034418 Genomic DNA. Translation: CAI17943.1.
AL034418 Genomic DNA. Translation: CAC17694.1. Sequence problems.
AL034418, AL354813 Genomic DNA. Translation: CAI42143.1.
CH471077 Genomic DNA. Translation: EAW75690.1.
CH471077 Genomic DNA. Translation: EAW75693.1.
CH471077 Genomic DNA. Translation: EAW75694.1.
CH471077 Genomic DNA. Translation: EAW75695.1.
BC020962 mRNA. Translation: AAH20962.1. Different initiation.
BC110539 mRNA. Translation: AAI10540.1.
AL133001 mRNA. Translation: CAB61349.1. Different initiation.
CCDSiCCDS13408.1. [Q8IWU5-1]
CCDS13409.2. [Q8IWU5-2]
RefSeqiNP_001155313.1. NM_001161841.1. [Q8IWU5-1]
NP_061325.1. NM_018837.3. [Q8IWU5-1]
NP_940998.2. NM_198596.2. [Q8IWU5-2]
XP_005260515.1. XM_005260458.1. [Q8IWU5-1]
XP_006723893.1. XM_006723830.1. [Q8IWU5-1]
UniGeneiHs.162016.

3D structure databases

ProteinModelPortaliQ8IWU5.
SMRiQ8IWU5. Positions 35-395.
ModBaseiSearch...
MobiDBiSearch...

Protein-protein interaction databases

BioGridi121010. 17 interactions.
IntActiQ8IWU5. 2 interactions.
STRINGi9606.ENSP00000353007.

PTM databases

iPTMnetiQ8IWU5.
PhosphoSiteiQ8IWU5.

Polymorphism and mutation databases

BioMutaiSULF2.
DMDMi33112446.

Proteomic databases

MaxQBiQ8IWU5.
PaxDbiQ8IWU5.
PRIDEiQ8IWU5.
TopDownProteomicsiQ8IWU5-2. [Q8IWU5-2]

Protocols and materials databases

DNASUi55959.
Structural Biology KnowledgebaseSearch...

Genome annotation databases

EnsembliENST00000359930; ENSP00000353007; ENSG00000196562. [Q8IWU5-1]
ENST00000467815; ENSP00000418442; ENSG00000196562. [Q8IWU5-2]
ENST00000484875; ENSP00000418290; ENSG00000196562. [Q8IWU5-1]
GeneIDi55959.
KEGGihsa:55959.
UCSCiuc002xto.4. human. [Q8IWU5-1]

Organism-specific databases

CTDi55959.
GeneCardsiSULF2.
H-InvDBHIX0027735.
HGNCiHGNC:20392. SULF2.
HPAiHPA002325.
MIMi610013. gene.
neXtProtiNX_Q8IWU5.
PharmGKBiPA134902131.
HUGEiSearch...
GenAtlasiSearch...

Phylogenomic databases

eggNOGiKOG3731. Eukaryota.
COG3119. LUCA.
GeneTreeiENSGT00400000022041.
HOVERGENiHBG056431.
InParanoidiQ8IWU5.
KOiK14607.
OMAiGEACACD.
OrthoDBiEOG7FR7H6.
PhylomeDBiQ8IWU5.
TreeFamiTF313545.

Miscellaneous databases

ChiTaRSiSULF2. human.
GeneWikiiSULF2.
GenomeRNAii55959.
PROiQ8IWU5.
SOURCEiSearch...

Gene expression databases

BgeeiQ8IWU5.
CleanExiHS_SULF2.
ExpressionAtlasiQ8IWU5. baseline and differential.
GenevisibleiQ8IWU5. HS.

Family and domain databases

Gene3Di3.40.720.10. 3 hits.
InterProiIPR017849. Alkaline_Pase-like_a/b/a.
IPR017850. Alkaline_phosphatase_core.
IPR014615. Extracellular_sulfatase.
IPR024609. Extracellular_sulfatase_C.
IPR024607. Sulfatase_CS.
IPR000917. Sulfatase_N.
[Graphical view]
PfamiPF12548. DUF3740. 1 hit.
PF00884. Sulfatase. 1 hit.
[Graphical view]
PIRSFiPIRSF036665. Sulf1. 1 hit.
SUPFAMiSSF53649. SSF53649. 3 hits.
PROSITEiPS00523. SULFATASE_1. 1 hit.
[Graphical view]
ProtoNetiSearch...

Publicationsi

« Hide 'large scale' publications
  1. "Cloning and characterization of two extracellular heparin-degrading endosulfatases in mice and humans."
    Morimoto-Tomita M., Uchimura K., Werb Z., Hemmerich S., Rosen S.D.
    J. Biol. Chem. 277:49175-49185(2002) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ISOFORM 1), CHARACTERIZATION, MUTAGENESIS OF 88-CYS-CYS-89.
    Tissue: Lung.
  2. "Prediction of the coding sequences of unidentified human genes. XV. The complete sequences of 100 new cDNA clones from brain which code for large proteins in vitro."
    Nagase T., Ishikawa K., Kikuno R., Hirosawa M., Nomura N., Ohara O.
    DNA Res. 6:337-345(1999) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA] (ISOFORM 1), VARIANT THR-76.
    Tissue: Brain.
  3. "Construction of expression-ready cDNA clones for KIAA genes: manual curation of 330 KIAA cDNA clones."
    Nakajima D., Okazaki N., Yamakawa H., Kikuno R., Ohara O., Nagase T.
    DNA Res. 9:99-106(2002) [PubMed] [Europe PMC] [Abstract]
    Cited for: SEQUENCE REVISION.
  4. Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA] (ISOFORM 2).
  5. Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA] (ISOFORM 1).
    Tissue: Fetal skin.
  6. "The DNA sequence and comparative analysis of human chromosome 20."
    Deloukas P., Matthews L.H., Ashurst J.L., Burton J., Gilbert J.G.R., Jones M., Stavrides G., Almeida J.P., Babbage A.K., Bagguley C.L., Bailey J., Barlow K.F., Bates K.N., Beard L.M., Beare D.M., Beasley O.P., Bird C.P., Blakey S.E.
    , Bridgeman A.M., Brown A.J., Buck D., Burrill W.D., Butler A.P., Carder C., Carter N.P., Chapman J.C., Clamp M., Clark G., Clark L.N., Clark S.Y., Clee C.M., Clegg S., Cobley V.E., Collier R.E., Connor R.E., Corby N.R., Coulson A., Coville G.J., Deadman R., Dhami P.D., Dunn M., Ellington A.G., Frankland J.A., Fraser A., French L., Garner P., Grafham D.V., Griffiths C., Griffiths M.N.D., Gwilliam R., Hall R.E., Hammond S., Harley J.L., Heath P.D., Ho S., Holden J.L., Howden P.J., Huckle E., Hunt A.R., Hunt S.E., Jekosch K., Johnson C.M., Johnson D., Kay M.P., Kimberley A.M., King A., Knights A., Laird G.K., Lawlor S., Lehvaeslaiho M.H., Leversha M.A., Lloyd C., Lloyd D.M., Lovell J.D., Marsh V.L., Martin S.L., McConnachie L.J., McLay K., McMurray A.A., Milne S.A., Mistry D., Moore M.J.F., Mullikin J.C., Nickerson T., Oliver K., Parker A., Patel R., Pearce T.A.V., Peck A.I., Phillimore B.J.C.T., Prathalingam S.R., Plumb R.W., Ramsay H., Rice C.M., Ross M.T., Scott C.E., Sehra H.K., Shownkeen R., Sims S., Skuce C.D., Smith M.L., Soderlund C., Steward C.A., Sulston J.E., Swann R.M., Sycamore N., Taylor R., Tee L., Thomas D.W., Thorpe A., Tracey A., Tromans A.C., Vaudin M., Wall M., Wallis J.M., Whitehead S.L., Whittaker P., Willey D.L., Williams L., Williams S.A., Wilming L., Wray P.W., Hubbard T., Durbin R.M., Bentley D.R., Beck S., Rogers J.
    Nature 414:865-871(2001) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
  7. Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
  8. "The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC)."
    The MGC Project Team
    Genome Res. 14:2121-2127(2004) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA] (ISOFORM 1).
    Tissue: Colon.
  9. Stavrides G.S., Huckle E.J., Deloukas P.
    Submitted (NOV-1999) to the EMBL/GenBank/DDBJ databases
    Cited for: NUCLEOTIDE SEQUENCE [MRNA] OF 527-870 (ISOFORM 1).
  10. "Glycoproteomics analysis of human liver tissue by combination of multiple enzyme digestion and hydrazide chemistry."
    Chen R., Jiang X., Sun D., Han G., Wang F., Ye M., Wang L., Zou H.
    J. Proteome Res. 8:651-661(2009) [PubMed] [Europe PMC] [Abstract]
    Cited for: GLYCOSYLATION [LARGE SCALE ANALYSIS] AT ASN-198.
    Tissue: Liver.
  11. Cited for: VARIANTS [LARGE SCALE ANALYSIS] HIS-531 AND ASN-573.

Entry informationi

Entry nameiSULF2_HUMAN
AccessioniPrimary (citable) accession number: Q8IWU5
Secondary accession number(s): E1P5U6
, Q5JYE1, Q6UX86, Q96SG2, Q9H1H0, Q9UJR3, Q9ULH3
Entry historyi
Integrated into UniProtKB/Swiss-Prot: July 19, 2003
Last sequence update: March 1, 2003
Last modified: June 8, 2016
This is version 126 of the entry and version 1 of the sequence. [Complete history]
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programChordata Protein Annotation Program
DisclaimerAny medical or genetic information present in this entry is provided for research, educational and informational purposes only. It is not in any way intended to be used as a substitute for professional medical advice, diagnosis, treatment or care.

Miscellaneousi

Keywords - Technical termi

Complete proteome, Reference proteome

Documents

  1. Human chromosome 20
    Human chromosome 20: entries, gene names and cross-references to MIM
  2. Human entries with polymorphisms or disease mutations
    List of human entries with polymorphisms or disease mutations
  3. Human polymorphisms and disease mutations
    Index of human polymorphisms and disease mutations
  4. MIM cross-references
    Online Mendelian Inheritance in Man (MIM) cross-references in UniProtKB/Swiss-Prot
  5. SIMILARITY comments
    Index of protein domains and families

Similar proteinsi

Links to similar proteins from the UniProt Reference Clusters (UniRef) at 100%, 90% and 50% sequence identity:
100%UniRef100 combines identical sequences and sub-fragments with 11 or more residues from any organism into one UniRef entry.
90%UniRef90 is built by clustering UniRef100 sequences that have at least 90% sequence identity to, and 80% overlap with, the longest sequence (a.k.a seed sequence).
50%UniRef50 is built by clustering UniRef90 seed sequences that have at least 50% sequence identity to, and 80% overlap with, the longest sequence in the cluster.