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Protein

HLA class I histocompatibility antigen, B-39 alpha chain

Gene

HLA-B

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

Functioni

Involved in the presentation of foreign antigens to the immune system.

GO - Molecular functioni

GO - Biological processi

Complete GO annotation...

Keywords - Biological processi

Host-virus interaction, Immunity

Enzyme and pathway databases

ReactomeiR-HSA-1236974. ER-Phagosome pathway.
R-HSA-1236977. Endosomal/Vacuolar pathway.
R-HSA-198933. Immunoregulatory interactions between a Lymphoid and a non-Lymphoid cell.
R-HSA-877300. Interferon gamma signaling.
R-HSA-909733. Interferon alpha/beta signaling.
R-HSA-983170. Antigen Presentation: Folding, assembly and peptide loading of class I MHC.

Names & Taxonomyi

Protein namesi
Recommended name:
HLA class I histocompatibility antigen, B-39 alpha chain
Alternative name(s):
MHC class I antigen B*39
Gene namesi
Name:HLA-B
Synonyms:HLAB
OrganismiHomo sapiens (Human)
Taxonomic identifieri9606 [NCBI]
Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaEuarchontogliresPrimatesHaplorrhiniCatarrhiniHominidaeHomo
Proteomesi
  • UP000005640 Componenti: Chromosome 6

Organism-specific databases

HGNCiHGNC:4932. HLA-B.

Subcellular locationi

Topology

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Topological domaini25 – 308284ExtracellularSequence analysisAdd
BLAST
Transmembranei309 – 33224HelicalSequence analysisAdd
BLAST
Topological domaini333 – 36230CytoplasmicSequence analysisAdd
BLAST

GO - Cellular componenti

Complete GO annotation...

Keywords - Cellular componenti

Membrane, MHC I

Pathology & Biotechi

Organism-specific databases

MalaCardsiHLA-B.

Polymorphism and mutation databases

DMDMi231398.

PTM / Processingi

Molecule processing

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Signal peptidei1 – 2424Add
BLAST
Chaini25 – 362338HLA class I histocompatibility antigen, B-39 alpha chainPRO_0000018843Add
BLAST

Amino acid modifications

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Glycosylationi110 – 1101N-linked (GlcNAc...)By similarity
Disulfide bondi125 ↔ 188PROSITE-ProRule annotation
Disulfide bondi227 ↔ 283PROSITE-ProRule annotation

Post-translational modificationi

Polyubiquitinated in a post ER compartment by interaction with human herpesvirus 8 MIR1 protein. This targets the protein for rapid degradation via the ubiquitin system (By similarity).By similarity

Keywords - PTMi

Disulfide bond, Glycoprotein, Ubl conjugation

Proteomic databases

EPDiP30475.
PaxDbiP30475.
PeptideAtlasiP30475.
PRIDEiP30475.

PTM databases

SwissPalmiP30475.

Expressioni

Gene expression databases

CleanExiHS_HLA-B.

Interactioni

Subunit structurei

Heterodimer of an alpha chain and a beta chain (beta-2-microglobulin). Interacts with human herpesvirus 8 MIR1 protein (By similarity).By similarity

Protein-protein interaction databases

STRINGi9606.ENSP00000399168.

Structurei

Secondary structure

1
362
Legend: HelixTurnBeta strand
Show more details
Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Beta strandi27 – 3610Combined sources
Beta strandi41 – 433Combined sources
Beta strandi45 – 528Combined sources
Beta strandi55 – 617Combined sources
Beta strandi64 – 663Combined sources
Helixi74 – 763Combined sources
Helixi81 – 10828Combined sources
Beta strandi113 – 1153Combined sources
Beta strandi118 – 12710Combined sources
Beta strandi133 – 14210Combined sources
Beta strandi145 – 1506Combined sources
Beta strandi157 – 1615Combined sources
Helixi162 – 17312Combined sources
Helixi176 – 18510Combined sources
Helixi187 – 19812Combined sources
Helixi200 – 2034Combined sources
Beta strandi210 – 2178Combined sources
Beta strandi219 – 23517Combined sources
Beta strandi238 – 2436Combined sources
Helixi249 – 2513Combined sources
Beta strandi252 – 2543Combined sources
Beta strandi261 – 2633Combined sources
Beta strandi265 – 27410Combined sources
Helixi278 – 2803Combined sources
Beta strandi281 – 2866Combined sources
Beta strandi290 – 2923Combined sources
Beta strandi294 – 2963Combined sources

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
EntryMethodResolution (Å)ChainPositionsPDBsum
4O2CX-ray1.80A25-298[»]
4O2EX-ray1.98A/D25-298[»]
4O2FX-ray1.90A/D25-298[»]
ProteinModelPortaliP30475.
SMRiP30475. Positions 25-298.
ModBaseiSearch...
MobiDBiSearch...

Family & Domainsi

Domains and Repeats

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Domaini209 – 29587Ig-like C1-typeAdd
BLAST

Region

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Regioni25 – 11490Alpha-1Add
BLAST
Regioni115 – 20692Alpha-2Add
BLAST
Regioni207 – 29892Alpha-3Add
BLAST
Regioni299 – 30810Connecting peptide

Sequence similaritiesi

Belongs to the MHC class I family.Curated

Keywords - Domaini

Signal, Transmembrane, Transmembrane helix

Phylogenomic databases

eggNOGiENOG410II5V. Eukaryota.
ENOG4111K8F. LUCA.
HOVERGENiHBG016709.

Family and domain databases

Gene3Di2.60.40.10. 1 hit.
3.30.500.10. 1 hit.
InterProiIPR007110. Ig-like_dom.
IPR013783. Ig-like_fold.
IPR003006. Ig/MHC_CS.
IPR003597. Ig_C1-set.
IPR011161. MHC_I-like_Ag-recog.
IPR011162. MHC_I/II-like_Ag-recog.
IPR027648. MHC_I_a.
IPR001039. MHC_I_a_a1/a2.
IPR010579. MHC_I_a_C.
[Graphical view]
PfamiPF07654. C1-set. 1 hit.
PF00129. MHC_I. 1 hit.
PF06623. MHC_I_C. 1 hit.
[Graphical view]
PRINTSiPR01638. MHCCLASSI.
SMARTiSM00407. IGc1. 1 hit.
[Graphical view]
SUPFAMiSSF48726. SSF48726. 1 hit.
SSF54452. SSF54452. 1 hit.
PROSITEiPS50835. IG_LIKE. 1 hit.
PS00290. IG_MHC. 1 hit.
[Graphical view]

Sequencei

Sequence statusi: Complete.

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

P30475-1 [UniParc]FASTAAdd to basket

« Hide

        10         20         30         40         50
MLVMAPRTVL LLLSAALALT ETWAGSHSMR YFYTSVSRPG RGEPRFISVG
60 70 80 90 100
YVDDTQFVRF DSDAASPREE PRAPWIEQEG PEYWDRNTQI CKTNTQTDRE
110 120 130 140 150
SLRNLRGYYN QSEAGSHTLQ RMYGCDVGPD GRLLRGHNQF AYDGKDYIAL
160 170 180 190 200
NEDLSSWTAA DTAAQITQRK WEAARVAEQL RTYLEGTCVE WLRRYLENGK
210 220 230 240 250
ETLQRADPPK THVTHHPISD HEATLRCWAL GFYPAEITLT WQRDGEDQTQ
260 270 280 290 300
DTELVETRPA GDRTFQKWAA VVVPSGEEQR YTCHVQHEGL PKPLTLRWEP
310 320 330 340 350
SSQSTVPIVG IVAGLAVLAV VVIGAVVAAV MCRRKSSGGK GGSYSQAASS
360
DSAQGSDVSL TA
Length:362
Mass (Da):40,328
Last modified:April 1, 1993 - v1
Checksum:i422698063DEAB039
GO

Polymorphismi

The following alleles of B-39 are known: B*39:01 (B39.1), B*39:02 (B9.2), B*39:03, B*39:04 (B39N), B*39:05 (ST-16), B*39:06 (B39G), B*39:07 (B39uw3), B*39:09, B*39:10, B*39:12 (B3901v), B*39:23 (B39022v1) and B*39:24. The sequence shown is that of B*39:01.

Natural variant

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Natural varianti4 – 41M → T.
Corresponds to variant rs1050458 [ dbSNP | Ensembl ].
VAR_056355
Natural varianti9 – 91V → L.
Corresponds to variant rs1050462 [ dbSNP | Ensembl ].
VAR_056356
Natural varianti17 – 171L → V.
Corresponds to variant rs1131165 [ dbSNP | Ensembl ].
VAR_056357
Natural varianti33 – 331Y → D in allele B*39:12.
VAR_016659
Natural varianti35 – 351S → A in allele B*39:04 and allele B*39:12.
Corresponds to variant rs1131170 [ dbSNP | Ensembl ].
VAR_016421
Natural varianti36 – 361V → M in allele B*39:04.
Corresponds to variant rs1050486 [ dbSNP | Ensembl ].
VAR_016660
Natural varianti48 – 481S → A.
Corresponds to variant rs713031 [ dbSNP | Ensembl ].
VAR_061410
Natural varianti48 – 481S → P.
Corresponds to variant rs713031 [ dbSNP | Ensembl ].
VAR_061411
Natural varianti48 – 481S → T.
Corresponds to variant rs713031 [ dbSNP | Ensembl ].
VAR_061412
Natural varianti65 – 651A → T.Combined sources
Corresponds to variant rs1050529 [ dbSNP | Ensembl ].
VAR_056358
Natural varianti87 – 871N → D.
Corresponds to variant rs1050570 [ dbSNP | Ensembl ].
VAR_056359
Natural varianti87 – 871N → E in allele B*39:02, allele B*39:08 and allele B*39:23; requires 2 nucleotide substitutions. Combined sources
VAR_016422
Natural varianti87 – 871N → K.
Corresponds to variant rs1065386 [ dbSNP | Ensembl ].
VAR_059479
Natural varianti91 – 911C → S in allele B*39:02, allele B*39:08 and allele B*39:23.
VAR_016423
Natural varianti91 – 911C → Y in allele B*39:10.
VAR_016424
Natural varianti97 – 971T → A.
Corresponds to variant rs1050393 [ dbSNP | Ensembl ].
VAR_056360
Natural varianti98 – 981D → Y in allele B*39:05, allele B*39:07 and allele B*39:08.
Corresponds to variant rs1131215 [ dbSNP | Ensembl ].
VAR_016425
Natural varianti119 – 1191L → W in allele B*39:06.
VAR_016426
Natural varianti121 – 1211R → S in allele B*39:03 and allele B*39:24.
VAR_016427
Natural varianti121 – 1211R → T in allele B*39:06.
VAR_016428
Natural varianti122 – 1221M → T in allele B*39:24.
VAR_016429
Natural varianti123 – 1231Y → S in allele B*39:09.
VAR_016430
Natural varianti138 – 1381N → D in allele B*39:07.
VAR_016431
Natural varianti140 – 1401F → S in allele B*39:07.
VAR_016432
Natural varianti168 – 1681Q → R in allele B*39:23.
VAR_016433
Natural varianti180 – 1801L → R in allele B*39:08.
VAR_016434
Natural varianti306 – 3061V → I.
Corresponds to variant rs1131500 [ dbSNP | Ensembl ].
VAR_056361
Natural varianti329 – 3291A → T.
Corresponds to variant rs1051488 [ dbSNP | Ensembl ].
VAR_056362

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
M94052 Genomic DNA. Translation: AAA52658.1.
M94051 Genomic DNA. Translation: AAA52660.1.
M94053 Genomic DNA. Translation: AAA52659.1.
U04243 mRNA. Translation: AAA87396.1.
L36318 mRNA. Translation: AAA73942.1.
L22649 Genomic DNA. Translation: AAA69861.1.
U29480 mRNA. Translation: AAC50392.1.
L42024 mRNA. Translation: AAB59484.1.
U29083 mRNA. Translation: AAC32741.1.
U56246 Genomic DNA. Translation: AAB01985.1.
Y09058 mRNA. Translation: CAA70261.1.
AB091216 Genomic DNA. Translation: BAC11810.1.
AB091218 Genomic DNA. Translation: BAC11811.1.
AF428252 mRNA. Translation: AAN63555.1.
L42280 Genomic DNA. Translation: AAB51452.1.
AH004887 Genomic DNA. Translation: AAB39108.1.
AB032097 Genomic DNA. Translation: BAA84116.1.
U15640 Genomic DNA. Translation: AAA74047.1.
PIRiI38876.
I54314.
I54505.
I68850.
I84488.
UniGeneiHs.654404.
Hs.77961.

Genome annotation databases

EnsembliENST00000425848; ENSP00000400842; ENSG00000223532.

Keywords - Coding sequence diversityi

Polymorphism

Cross-referencesi

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
M94052 Genomic DNA. Translation: AAA52658.1.
M94051 Genomic DNA. Translation: AAA52660.1.
M94053 Genomic DNA. Translation: AAA52659.1.
U04243 mRNA. Translation: AAA87396.1.
L36318 mRNA. Translation: AAA73942.1.
L22649 Genomic DNA. Translation: AAA69861.1.
U29480 mRNA. Translation: AAC50392.1.
L42024 mRNA. Translation: AAB59484.1.
U29083 mRNA. Translation: AAC32741.1.
U56246 Genomic DNA. Translation: AAB01985.1.
Y09058 mRNA. Translation: CAA70261.1.
AB091216 Genomic DNA. Translation: BAC11810.1.
AB091218 Genomic DNA. Translation: BAC11811.1.
AF428252 mRNA. Translation: AAN63555.1.
L42280 Genomic DNA. Translation: AAB51452.1.
AH004887 Genomic DNA. Translation: AAB39108.1.
AB032097 Genomic DNA. Translation: BAA84116.1.
U15640 Genomic DNA. Translation: AAA74047.1.
PIRiI38876.
I54314.
I54505.
I68850.
I84488.
UniGeneiHs.654404.
Hs.77961.

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
EntryMethodResolution (Å)ChainPositionsPDBsum
4O2CX-ray1.80A25-298[»]
4O2EX-ray1.98A/D25-298[»]
4O2FX-ray1.90A/D25-298[»]
ProteinModelPortaliP30475.
SMRiP30475. Positions 25-298.
ModBaseiSearch...
MobiDBiSearch...

Protein-protein interaction databases

STRINGi9606.ENSP00000399168.

PTM databases

SwissPalmiP30475.

Polymorphism and mutation databases

DMDMi231398.

Proteomic databases

EPDiP30475.
PaxDbiP30475.
PeptideAtlasiP30475.
PRIDEiP30475.

Protocols and materials databases

Structural Biology KnowledgebaseSearch...

Genome annotation databases

EnsembliENST00000425848; ENSP00000400842; ENSG00000223532.

Organism-specific databases

GeneCardsiHLA-B.
HGNCiHGNC:4932. HLA-B.
MalaCardsiHLA-B.
MIMi142830. gene.
neXtProtiNX_P30475.
GenAtlasiSearch...

Phylogenomic databases

eggNOGiENOG410II5V. Eukaryota.
ENOG4111K8F. LUCA.
HOVERGENiHBG016709.

Enzyme and pathway databases

ReactomeiR-HSA-1236974. ER-Phagosome pathway.
R-HSA-1236977. Endosomal/Vacuolar pathway.
R-HSA-198933. Immunoregulatory interactions between a Lymphoid and a non-Lymphoid cell.
R-HSA-877300. Interferon gamma signaling.
R-HSA-909733. Interferon alpha/beta signaling.
R-HSA-983170. Antigen Presentation: Folding, assembly and peptide loading of class I MHC.

Miscellaneous databases

ChiTaRSiHLA-B. human.
SOURCEiSearch...

Gene expression databases

CleanExiHS_HLA-B.

Family and domain databases

Gene3Di2.60.40.10. 1 hit.
3.30.500.10. 1 hit.
InterProiIPR007110. Ig-like_dom.
IPR013783. Ig-like_fold.
IPR003006. Ig/MHC_CS.
IPR003597. Ig_C1-set.
IPR011161. MHC_I-like_Ag-recog.
IPR011162. MHC_I/II-like_Ag-recog.
IPR027648. MHC_I_a.
IPR001039. MHC_I_a_a1/a2.
IPR010579. MHC_I_a_C.
[Graphical view]
PfamiPF07654. C1-set. 1 hit.
PF00129. MHC_I. 1 hit.
PF06623. MHC_I_C. 1 hit.
[Graphical view]
PRINTSiPR01638. MHCCLASSI.
SMARTiSM00407. IGc1. 1 hit.
[Graphical view]
SUPFAMiSSF48726. SSF48726. 1 hit.
SSF54452. SSF54452. 1 hit.
PROSITEiPS50835. IG_LIKE. 1 hit.
PS00290. IG_MHC. 1 hit.
[Graphical view]
ProtoNetiSearch...

Publicationsi

« Hide 'large scale' publications
  1. Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA] (ALLELES B*39:01 AND B*39:02).
  2. "HLA-B16 antigens: sequence of the ST-16 antigen, further definition of two B38 subtypes and evidence for convergent evolution of B*3902."
    Adams E.J., Martinez-Naves E., Arnett K.L., Little A.-M., Tyan D.B., Parham P.
    Tissue Antigens 45:18-26(1995) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ALLELES B*39:02 AND B*39:05).
  3. "Identification of the gene encoding a novel HLA-B39 subtype. Two amino acid substitutions on the beta-sheet out of the peptide-binding floor form a novel serological epitope."
    Ogawa A., Tokunaga K., Nakajima F., Kikuchi A., Karaki S., Kashiwase K., Ge J., Hannestad K., Juji T., Takiguchi M.
    Hum. Immunol. 41:241-247(1994) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA] (ALLELE B*39:04).
    Tissue: Peripheral blood.
  4. "Primary structure of a novel HLA-B39 allele (B*3909) from the Warao Indians of Venezuela. Further evidence for local HLA-B diversification in South America."
    Ramos M., Postigo J.M., Vilches C., Layrisse Z., Lopez de Castro J.A.
    Tissue Antigens 46:401-404(1995) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ALLELE B*39:09).
    Tissue: Blood.
  5. Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ALLELE B*39:06).
  6. Zhang L., Ellexson M.E., Hildebrand W.H.
    Submitted (JUN-1995) to the EMBL/GenBank/DDBJ databases
    Cited for: NUCLEOTIDE SEQUENCE (ALLELE B*39:06).
  7. "A novel recombinant HLA-B*39 allele (B*3910) in a South African Zulu."
    Wells R.S., Parham P.
    Tissue Antigens 48:595-597(1996) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA] (ALLELE B*39:10).
  8. "The novel HLA-Cw*1802 allele is associated with B*5703 in the Bubi population from Equatorial Guinea."
    Vilches C., Bunce M., de Pablo R., Moreno M.E., Puente S., Sanz L., Kreisler M.
    Tissue Antigens 49:644-648(1997) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ALLELE B*39:10).
  9. Kashiwase K.
    Submitted (SEP-2002) to the EMBL/GenBank/DDBJ databases
    Cited for: NUCLEOTIDE SEQUENCE (ALLELE B*39:01).
  10. Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ALLELE B*39:24).
    Tissue: Peripheral blood.
  11. Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA] OF 10-362 (ALLELE B*39:08).
  12. Cited for: NUCLEOTIDE SEQUENCE OF 26-206 (ALLELE B*39:12).
  13. "Evolution of HLA-class I compared to HLA-class II polymorphism in Terena, a South-American Indian tribe."
    Lazaro A.M., Moraes M.E., Marcos C.Y., Moraes J.R., Fernandez-Vina M.A., Stastny P.
    Hum. Immunol. 60:1138-1149(1999) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE OF 26-206 (ALLELE B*39:12).
  14. "Allele frequency of HLA-B39 in the Japanese population and identification of a novel B39 allele, B*3923."
    Akesaka T., Kashiwase K., Ishikawa Y., Tanaka H., Shimizu M., Kawai S., Akaza T., Takahashi T., Juji T.
    Tissue Antigens 57:169-172(2001) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA] OF 26-206 (ALLELE B*39:23).
  15. Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA] OF 60-196 (ALLELE B*39:07).
  16. Cited for: IDENTIFICATION BY MASS SPECTROMETRY [LARGE SCALE ANALYSIS].
  17. Cited for: VARIANT [LARGE SCALE ANALYSIS] THR-65, IDENTIFICATION BY MASS SPECTROMETRY [LARGE SCALE ANALYSIS].
  18. "An enzyme assisted RP-RPLC approach for in-depth analysis of human liver phosphoproteome."
    Bian Y., Song C., Cheng K., Dong M., Wang F., Huang J., Sun D., Wang L., Ye M., Zou H.
    J. Proteomics 96:253-262(2014) [PubMed] [Europe PMC] [Abstract]
    Cited for: VARIANT [LARGE SCALE ANALYSIS] GLU-87, IDENTIFICATION BY MASS SPECTROMETRY [LARGE SCALE ANALYSIS].
    Tissue: Liver.

Entry informationi

Entry namei1B39_HUMAN
AccessioniPrimary (citable) accession number: P30475
Secondary accession number(s): O02960
, O78217, P30476, P79504, Q29665, Q29697, Q29749, Q29847, Q29852, Q29858, Q8HWF0, Q9TPQ7
Entry historyi
Integrated into UniProtKB/Swiss-Prot: April 1, 1993
Last sequence update: April 1, 1993
Last modified: July 6, 2016
This is version 138 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

3D-structure, Complete proteome, Reference proteome

Documents

  1. Human chromosome 6
    Human chromosome 6: 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. PDB cross-references
    Index of Protein Data Bank (PDB) cross-references
  6. 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.