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Protein

Semaphorin-7A

Gene

SEMA7A

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

Functioni

Plays an important role in integrin-mediated signaling and functions both in regulating cell migration and immune responses. Promotes formation of focal adhesion complexes, activation of the protein kinase PTK2/FAK1 and subsequent phosphorylation of MAPK1 and MAPK3. Promotes production of proinflammatory cytokines by monocytes and macrophages. Plays an important role in modulating inflammation and T-cell-mediated immune responses. Promotes axon growth in the embryonic olfactory bulb. Promotes attachment, spreading and dendrite outgrowth in melanocytes.3 Publications

GO - Molecular functioni

GO - Biological processi

  • axon extension Source: Ensembl
  • immune response Source: ProtInc
  • inflammatory response Source: UniProtKB-KW
  • integrin-mediated signaling pathway Source: UniProtKB
  • neural crest cell migration Source: GO_Central
  • olfactory lobe development Source: Ensembl
  • osteoblast differentiation Source: UniProtKB
  • positive regulation of axon extension Source: UniProtKB
  • positive regulation of cell migration Source: GO_Central
  • positive regulation of ERK1 and ERK2 cascade Source: UniProtKB
  • positive regulation of macrophage cytokine production Source: UniProtKB
  • regulation of inflammatory response Source: UniProtKB
Complete GO annotation...

Keywords - Molecular functioni

Developmental protein

Keywords - Biological processi

Differentiation, Inflammatory response, Neurogenesis

Enzyme and pathway databases

BioCyciZFISH:ENSG00000138623-MONOMER.
ReactomeiR-HSA-416700. Other semaphorin interactions.
SIGNORiO75326.

Names & Taxonomyi

Protein namesi
Recommended name:
Semaphorin-7A
Alternative name(s):
CDw108
JMH blood group antigen
John-Milton-Hargen human blood group Ag
Semaphorin-K1
Short name:
Sema K1
Semaphorin-L
Short name:
Sema L
CD_antigen: CD108
Gene namesi
Name:SEMA7A
Synonyms:CD108, SEMAL
OrganismiHomo sapiens (Human)
Taxonomic identifieri9606 [NCBI]
Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaEuarchontogliresPrimatesHaplorrhiniCatarrhiniHominidaeHomo
Proteomesi
  • UP000005640 Componenti: Chromosome 15

Organism-specific databases

HGNCiHGNC:10741. SEMA7A.

Subcellular locationi

GO - Cellular componenti

Complete GO annotation...

Keywords - Cellular componenti

Cell membrane, Membrane

Pathology & Biotechi

Mutagenesis

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Mutagenesisi267R → K: Abolishes ITGB1-dependent enhancement of axon growth; when associated with E-269. 1 Publication1
Mutagenesisi269D → E: Abolishes ITGB1-dependent enhancement of axon growth; when associated with K-267. 1 Publication1

Organism-specific databases

DisGeNETi8482.
MIMi607961. gene+phenotype.
614745. phenotype.
OpenTargetsiENSG00000138623.
PharmGKBiPA35663.

Polymorphism and mutation databases

BioMutaiSEMA7A.

PTM / Processingi

Molecule processing

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Signal peptidei1 – 44Sequence analysisAdd BLAST44
ChainiPRO_000003234745 – 648Semaphorin-7AAdd BLAST604
PropeptideiPRO_0000032348649 – 666Removed in mature formSequence analysisAdd BLAST18

Amino acid modifications

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Glycosylationi105N-linked (GlcNAc...)1 Publication1
Disulfide bondi120 ↔ 1261 Publication
Modified residuei135Asymmetric dimethylarginineBy similarity1
Disulfide bondi143 ↔ 1521 Publication
Glycosylationi157N-linked (GlcNAc...)1 Publication1
Glycosylationi258N-linked (GlcNAc...)1 Publication1
Disulfide bondi266 ↔ 3661 Publication
Disulfide bondi291 ↔ 3351 Publication
Glycosylationi330N-linked (GlcNAc...)1 Publication1
Disulfide bondi493 ↔ 5111 Publication
Disulfide bondi500 ↔ 5411 Publication
Disulfide bondi503 ↔ 5181 Publication
Disulfide bondi566 ↔ 6131 Publication
Disulfide bondi587 ↔ 5961 Publication
Glycosylationi602N-linked (GlcNAc...)1 Publication1
Lipidationi648GPI-anchor amidated alanineSequence analysis1

Keywords - PTMi

Disulfide bond, Glycoprotein, GPI-anchor, Lipoprotein, Methylation

Proteomic databases

EPDiO75326.
MaxQBiO75326.
PaxDbiO75326.
PeptideAtlasiO75326.
PRIDEiO75326.

PTM databases

iPTMnetiO75326.
PhosphoSitePlusiO75326.
SwissPalmiO75326.

Expressioni

Tissue specificityi

Detected in skin keratinocytes and on endothelial cells from skin blood vessels (at protein level). Expressed in fibroblasts, keratinocytes, melanocytes, placenta, testis, ovary, spleen, brain, spinal chord, lung, heart, adrenal gland, lymph nodes, thymus, intestine and kidney.3 Publications

Inductioni

Up-regulated in UV-irradiated fibroblasts, but not in UV-irradiated keratinocytes.1 Publication

Gene expression databases

BgeeiENSG00000138623.
CleanExiHS_SEMA7A.
ExpressionAtlasiO75326. baseline and differential.
GenevisibleiO75326. HS.

Organism-specific databases

HPAiHPA042273.

Interactioni

Subunit structurei

Interacts with ITGA1 and ITGB1 (Probable). Interacts with PLXNC1.Curated4 Publications

Binary interactionsi

WithEntry#Exp.IntActNotes
NCK1P163332EBI-1753538,EBI-389883
PLXNC1O604864EBI-1753538,EBI-2927384

GO - Molecular functioni

Protein-protein interaction databases

BioGridi114056. 14 interactors.
IntActiO75326. 6 interactors.
MINTiMINT-1958248.
STRINGi9606.ENSP00000261918.

Structurei

Secondary structure

1666
Legend: HelixTurnBeta strandPDB Structure known for this area
Show more details
Feature keyPosition(s)DescriptionActionsGraphical viewLength
Turni62 – 64Combined sources3
Beta strandi65 – 68Combined sources4
Beta strandi77 – 79Combined sources3
Beta strandi85 – 90Combined sources6
Beta strandi92 – 99Combined sources8
Beta strandi110 – 112Combined sources3
Beta strandi129 – 136Combined sources8
Beta strandi139 – 144Combined sources6
Turni146 – 148Combined sources3
Beta strandi151 – 158Combined sources8
Beta strandi160 – 165Combined sources6
Beta strandi180 – 183Combined sources4
Beta strandi186 – 189Combined sources4
Beta strandi204 – 210Combined sources7
Beta strandi223 – 230Combined sources8
Helixi235 – 237Combined sources3
Beta strandi239 – 247Combined sources9
Beta strandi257 – 266Combined sources10
Beta strandi272 – 274Combined sources3
Turni275 – 279Combined sources5
Beta strandi285 – 289Combined sources5
Turni294 – 296Combined sources3
Beta strandi302 – 309Combined sources8
Helixi316 – 318Combined sources3
Beta strandi320 – 326Combined sources7
Beta strandi332 – 338Combined sources7
Helixi339 – 348Combined sources10
Beta strandi368 – 370Combined sources3
Helixi375 – 383Combined sources9
Beta strandi386 – 389Combined sources4
Beta strandi394 – 397Combined sources4
Beta strandi401 – 406Combined sources6
Beta strandi408 – 417Combined sources10
Beta strandi423 – 431Combined sources9
Beta strandi436 – 440Combined sources5
Beta strandi451 – 456Combined sources6
Beta strandi467 – 471Combined sources5
Turni472 – 475Combined sources4
Beta strandi476 – 480Combined sources5
Beta strandi482 – 489Combined sources8
Helixi499 – 505Combined sources7
Beta strandi511 – 514Combined sources4
Beta strandi517 – 520Combined sources4
Beta strandi523 – 526Combined sources4
Beta strandi533 – 535Combined sources3
Turni537 – 540Combined sources4
Beta strandi541 – 545Combined sources5
Beta strandi551 – 556Combined sources6
Beta strandi562 – 567Combined sources6
Beta strandi573 – 579Combined sources7
Beta strandi582 – 587Combined sources6
Beta strandi592 – 602Combined sources11
Beta strandi609 – 619Combined sources11
Beta strandi621 – 631Combined sources11

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
PDB entryMethodResolution (Å)ChainPositionsPDBsum
3NVQX-ray2.40A/E45-634[»]
ProteinModelPortaliO75326.
SMRiO75326.
ModBaseiSearch...
MobiDBiSearch...

Miscellaneous databases

EvolutionaryTraceiO75326.

Family & Domainsi

Domains and Repeats

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Domaini53 – 490SemaPROSITE-ProRule annotationAdd BLAST438
Domaini544 – 629Ig-like C2-typeAdd BLAST86

Region

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Regioni267 – 269Interaction with integrins3

Motif

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Motifi267 – 269Cell attachment siteSequence analysis3

Sequence similaritiesi

Belongs to the semaphorin family.Curated
Contains 1 PSI domain.Curated
Contains 1 Sema domain.PROSITE-ProRule annotation

Keywords - Domaini

Immunoglobulin domain, Signal

Phylogenomic databases

eggNOGiKOG3611. Eukaryota.
ENOG410XQZC. LUCA.
GeneTreeiENSGT00760000119134.
HOGENOMiHOG000154284.
HOVERGENiHBG079171.
InParanoidiO75326.
KOiK06529.
OMAiEPMGPLK.
OrthoDBiEOG091G01W0.
PhylomeDBiO75326.
TreeFamiTF333698.

Family and domain databases

Gene3Di2.130.10.10. 1 hit.
2.60.40.10. 1 hit.
InterProiIPR007110. Ig-like_dom.
IPR013783. Ig-like_fold.
IPR002165. Plexin_repeat.
IPR016201. PSI.
IPR001627. Semap_dom.
IPR027231. Semaphorin.
IPR015943. WD40/YVTN_repeat-like_dom.
[Graphical view]
PANTHERiPTHR11036. PTHR11036. 1 hit.
PfamiPF13895. Ig_2. 1 hit.
PF01437. PSI. 1 hit.
PF01403. Sema. 1 hit.
[Graphical view]
SMARTiSM00423. PSI. 1 hit.
SM00630. Sema. 1 hit.
[Graphical view]
SUPFAMiSSF101912. SSF101912. 1 hit.
SSF48726. SSF48726. 1 hit.
PROSITEiPS50835. IG_LIKE. 1 hit.
PS51004. SEMA. 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: O75326-1) [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
MTPPPPGRAA PSAPRARVPG PPARLGLPLR LRLLLLLWAA AASAQGHLRS
60 70 80 90 100
GPRIFAVWKG HVGQDRVDFG QTEPHTVLFH EPGSSSVWVG GRGKVYLFDF
110 120 130 140 150
PEGKNASVRT VNIGSTKGSC LDKRDCENYI TLLERRSEGL LACGTNARHP
160 170 180 190 200
SCWNLVNGTV VPLGEMRGYA PFSPDENSLV LFEGDEVYST IRKQEYNGKI
210 220 230 240 250
PRFRRIRGES ELYTSDTVMQ NPQFIKATIV HQDQAYDDKI YYFFREDNPD
260 270 280 290 300
KNPEAPLNVS RVAQLCRGDQ GGESSLSVSK WNTFLKAMLV CSDAATNKNF
310 320 330 340 350
NRLQDVFLLP DPSGQWRDTR VYGVFSNPWN YSAVCVYSLG DIDKVFRTSS
360 370 380 390 400
LKGYHSSLPN PRPGKCLPDQ QPIPTETFQV ADRHPEVAQR VEPMGPLKTP
410 420 430 440 450
LFHSKYHYQK VAVHRMQASH GETFHVLYLT TDRGTIHKVV EPGEQEHSFA
460 470 480 490 500
FNIMEIQPFR RAAAIQTMSL DAERRKLYVS SQWEVSQVPL DLCEVYGGGC
510 520 530 540 550
HGCLMSRDPY CGWDQGRCIS IYSSERSVLQ SINPAEPHKE CPNPKPDKAP
560 570 580 590 600
LQKVSLAPNS RYYLSCPMES RHATYSWRHK ENVEQSCEPG HQSPNCILFI
610 620 630 640 650
ENLTAQQYGH YFCEAQEGSY FREAQHWQLL PEDGIMAEHL LGHACALAAS
660
LWLGVLPTLT LGLLVH
Length:666
Mass (Da):74,824
Last modified:November 1, 1998 - v1
Checksum:iAD3ABE56B5EBE194
GO
Isoform 2 (identifier: O75326-2) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     111-124: Missing.

Note: No experimental confirmation available.
Show »
Length:652
Mass (Da):73,364
Checksum:i0EB0B9085C9DCCA0
GO

Experimental Info

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Sequence conflicti545K → E in BAG56808 (PubMed:14702039).Curated1

Polymorphismi

Genetic variations in SEMA7A define the John Milton Hagen blood group system (JMH) [MIMi:614745]. Three different JMH phenotypes have been identified based on the presence or absence of the high-frequency JMH antigen: JMH-weak, JMH-negative, and JMH-variant. The JMH-weak and -negative phenotypes can be either acquired or inherited and are characterized by a reduction or complete loss of JMH expression on red blood cells. Individuals with the JMH-variant phenotype are usually JMH-positive and have alloantibodies compatible with JMH-negative red blood cells. The JMH-variant phenotype results from rare SEMA7A missense variants.1 Publication

Natural variant

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Natural variantiVAR_029282115S → T.1 PublicationCorresponds to variant rs16968733dbSNPEnsembl.1
Natural variantiVAR_038836207R → Q Rare polymorphism that results in JMH-variant phenotype. 1 PublicationCorresponds to variant rs55637216dbSNPEnsembl.1
Natural variantiVAR_038837207R → W Rare polymorphism that results in JMH-variant phenotype. 1 PublicationCorresponds to variant rs56367230dbSNPEnsembl.1
Natural variantiVAR_068679347R → L Rare polymorphism that results in JMH-variant phenotype. 1 PublicationCorresponds to variant rs387907241dbSNPEnsembl.1
Natural variantiVAR_038838460R → H Rare polymorphism that results in JMH-variant phenotype. 1 PublicationCorresponds to variant rs56204206dbSNPEnsembl.1
Natural variantiVAR_038839461R → C Rare polymorphism that results in JMH-variant phenotype. 1 PublicationCorresponds to variant rs56001514dbSNPEnsembl.1

Alternative sequence

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Alternative sequenceiVSP_045349111 – 124Missing in isoform 2. 1 PublicationAdd BLAST14

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
AF030698 mRNA. Translation: AAC34261.1.
AF030697 Genomic DNA. Translation: AAC34741.1.
AF069493 mRNA. Translation: AAC82642.1.
AF071542 mRNA. Translation: AAC80456.1.
AM180445 mRNA. Translation: CAJ55398.1.
AM180446 mRNA. Translation: CAJ55399.1.
AM180447 mRNA. Translation: CAJ55400.1.
AM180448 mRNA. Translation: CAJ55401.1.
AM180449 mRNA. Translation: CAJ55402.1.
AM180450 mRNA. Translation: CAJ55403.1.
AM180451 mRNA. Translation: CAJ55404.1.
AK293280 mRNA. Translation: BAG56808.1.
AY885237 Genomic DNA. Translation: AAW62253.1.
AC012435 Genomic DNA. No translation available.
AC090826 Genomic DNA. No translation available.
BC101643 mRNA. Translation: AAI01644.1.
BC101647 mRNA. Translation: AAI01648.1.
CCDSiCCDS10262.1. [O75326-1]
CCDS53959.1. [O75326-2]
RefSeqiNP_001139501.1. NM_001146029.2. [O75326-2]
NP_001139502.1. NM_001146030.2.
NP_003603.1. NM_003612.4. [O75326-1]
UniGeneiHs.24640.

Genome annotation databases

EnsembliENST00000261918; ENSP00000261918; ENSG00000138623. [O75326-1]
ENST00000543145; ENSP00000438966; ENSG00000138623. [O75326-2]
GeneIDi8482.
KEGGihsa:8482.
UCSCiuc002axv.4. human. [O75326-1]

Keywords - Coding sequence diversityi

Alternative splicing, Polymorphism

Cross-referencesi

Web resourcesi

dbRBC/BGMUT

Blood group antigen gene mutation database

SeattleSNPs

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
AF030698 mRNA. Translation: AAC34261.1.
AF030697 Genomic DNA. Translation: AAC34741.1.
AF069493 mRNA. Translation: AAC82642.1.
AF071542 mRNA. Translation: AAC80456.1.
AM180445 mRNA. Translation: CAJ55398.1.
AM180446 mRNA. Translation: CAJ55399.1.
AM180447 mRNA. Translation: CAJ55400.1.
AM180448 mRNA. Translation: CAJ55401.1.
AM180449 mRNA. Translation: CAJ55402.1.
AM180450 mRNA. Translation: CAJ55403.1.
AM180451 mRNA. Translation: CAJ55404.1.
AK293280 mRNA. Translation: BAG56808.1.
AY885237 Genomic DNA. Translation: AAW62253.1.
AC012435 Genomic DNA. No translation available.
AC090826 Genomic DNA. No translation available.
BC101643 mRNA. Translation: AAI01644.1.
BC101647 mRNA. Translation: AAI01648.1.
CCDSiCCDS10262.1. [O75326-1]
CCDS53959.1. [O75326-2]
RefSeqiNP_001139501.1. NM_001146029.2. [O75326-2]
NP_001139502.1. NM_001146030.2.
NP_003603.1. NM_003612.4. [O75326-1]
UniGeneiHs.24640.

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
PDB entryMethodResolution (Å)ChainPositionsPDBsum
3NVQX-ray2.40A/E45-634[»]
ProteinModelPortaliO75326.
SMRiO75326.
ModBaseiSearch...
MobiDBiSearch...

Protein-protein interaction databases

BioGridi114056. 14 interactors.
IntActiO75326. 6 interactors.
MINTiMINT-1958248.
STRINGi9606.ENSP00000261918.

PTM databases

iPTMnetiO75326.
PhosphoSitePlusiO75326.
SwissPalmiO75326.

Polymorphism and mutation databases

BioMutaiSEMA7A.

Proteomic databases

EPDiO75326.
MaxQBiO75326.
PaxDbiO75326.
PeptideAtlasiO75326.
PRIDEiO75326.

Protocols and materials databases

Structural Biology KnowledgebaseSearch...

Genome annotation databases

EnsembliENST00000261918; ENSP00000261918; ENSG00000138623. [O75326-1]
ENST00000543145; ENSP00000438966; ENSG00000138623. [O75326-2]
GeneIDi8482.
KEGGihsa:8482.
UCSCiuc002axv.4. human. [O75326-1]

Organism-specific databases

CTDi8482.
DisGeNETi8482.
GeneCardsiSEMA7A.
HGNCiHGNC:10741. SEMA7A.
HPAiHPA042273.
MIMi607961. gene+phenotype.
614745. phenotype.
neXtProtiNX_O75326.
OpenTargetsiENSG00000138623.
PharmGKBiPA35663.
GenAtlasiSearch...

Phylogenomic databases

eggNOGiKOG3611. Eukaryota.
ENOG410XQZC. LUCA.
GeneTreeiENSGT00760000119134.
HOGENOMiHOG000154284.
HOVERGENiHBG079171.
InParanoidiO75326.
KOiK06529.
OMAiEPMGPLK.
OrthoDBiEOG091G01W0.
PhylomeDBiO75326.
TreeFamiTF333698.

Enzyme and pathway databases

BioCyciZFISH:ENSG00000138623-MONOMER.
ReactomeiR-HSA-416700. Other semaphorin interactions.
SIGNORiO75326.

Miscellaneous databases

ChiTaRSiSEMA7A. human.
EvolutionaryTraceiO75326.
GeneWikiiSEMA7A.
GenomeRNAii8482.
PROiO75326.
SOURCEiSearch...

Gene expression databases

BgeeiENSG00000138623.
CleanExiHS_SEMA7A.
ExpressionAtlasiO75326. baseline and differential.
GenevisibleiO75326. HS.

Family and domain databases

Gene3Di2.130.10.10. 1 hit.
2.60.40.10. 1 hit.
InterProiIPR007110. Ig-like_dom.
IPR013783. Ig-like_fold.
IPR002165. Plexin_repeat.
IPR016201. PSI.
IPR001627. Semap_dom.
IPR027231. Semaphorin.
IPR015943. WD40/YVTN_repeat-like_dom.
[Graphical view]
PANTHERiPTHR11036. PTHR11036. 1 hit.
PfamiPF13895. Ig_2. 1 hit.
PF01437. PSI. 1 hit.
PF01403. Sema. 1 hit.
[Graphical view]
SMARTiSM00423. PSI. 1 hit.
SM00630. Sema. 1 hit.
[Graphical view]
SUPFAMiSSF101912. SSF101912. 1 hit.
SSF48726. SSF48726. 1 hit.
PROSITEiPS50835. IG_LIKE. 1 hit.
PS51004. SEMA. 1 hit.
[Graphical view]
ProtoNetiSearch...

Entry informationi

Entry nameiSEM7A_HUMAN
AccessioniPrimary (citable) accession number: O75326
Secondary accession number(s): B4DDP7
, F5H1S0, Q1XE81, Q1XE82, Q1XE83, Q1XE84, Q3MIY5
Entry historyi
Integrated into UniProtKB/Swiss-Prot: June 20, 2001
Last sequence update: November 1, 1998
Last modified: November 30, 2016
This is version 157 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. Blood group antigen proteins
    Nomenclature of blood group antigens and list of entries
  2. Human cell differentiation molecules
    CD nomenclature of surface proteins of human leucocytes and list of entries
  3. Human chromosome 15
    Human chromosome 15: entries, gene names and cross-references to MIM
  4. Human entries with polymorphisms or disease mutations
    List of human entries with polymorphisms or disease mutations
  5. Human polymorphisms and disease mutations
    Index of human polymorphisms and disease mutations
  6. MIM cross-references
    Online Mendelian Inheritance in Man (MIM) cross-references in UniProtKB/Swiss-Prot
  7. PDB cross-references
    Index of Protein Data Bank (PDB) cross-references
  8. 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.