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Protein

Methionine aminopeptidase 2

Gene

METAP2

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

Functioni

Cotranslationally removes the N-terminal methionine from nascent proteins. The N-terminal methionine is often cleaved when the second residue in the primary sequence is small and uncharged (Met-Ala-, Cys, Gly, Pro, Ser, Thr, or Val). The catalytic activity of human METAP2 toward Met-Val peptides is consistently two orders of magnitude higher than that of METAP1, suggesting that it is responsible for processing proteins containing N-terminal Met-Val and Met-Thr sequences in vivo.
Protects eukaryotic initiation factor EIF2S1 from translation-inhibiting phosphorylation by inhibitory kinases such as EIF2AK2/PKR and EIF2AK1/HCR. Plays a critical role in the regulation of protein synthesis.

Catalytic activityi

Release of N-terminal amino acids, preferentially methionine, from peptides and arylamides.UniRule annotation1 Publication

Cofactori

Co2+UniRule annotation3 Publications, Zn2+UniRule annotation3 Publications, Mn2+UniRule annotation3 Publications, Fe2+UniRule annotation3 PublicationsNote: Binds 2 divalent metal cations per subunit. Has a high-affinity and a low affinity metal-binding site. The true nature of the physiological cofactor is under debate. The enzyme is active with cobalt, zinc, manganese or divalent iron ions. Most likely, methionine aminopeptidases function as mononuclear Fe2+-metalloproteases under physiological conditions, and the catalytically relevant metal-binding site has been assigned to the histidine-containing high-affinity site. Also manganese has been proposed to be the physiological cofactor for human METAP2.UniRule annotation3 Publications

Sites

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Binding sitei231SubstrateUniRule annotation1 Publication1
Metal bindingi251Divalent metal cation 1UniRule annotation5 Publications1
Metal bindingi262Divalent metal cation 1UniRule annotation5 Publications1
Metal bindingi262Divalent metal cation 2; catalyticUniRule annotation5 Publications1
Metal bindingi331Divalent metal cation 2; catalytic; via tele nitrogenUniRule annotation5 Publications1
Binding sitei339SubstrateUniRule annotation1 Publication1
Metal bindingi364Divalent metal cation 2; catalyticUniRule annotation5 Publications1
Metal bindingi459Divalent metal cation 1UniRule annotation5 Publications1
Metal bindingi459Divalent metal cation 2; catalyticUniRule annotation5 Publications1

GO - Molecular functioni

  • aminopeptidase activity Source: UniProtKB
  • metal ion binding Source: UniProtKB-HAMAP
  • metalloaminopeptidase activity Source: UniProtKB-HAMAP
  • metalloexopeptidase activity Source: UniProtKB
  • poly(A) RNA binding Source: UniProtKB

GO - Biological processi

  • N-terminal protein amino acid modification Source: HGNC
  • peptidyl-methionine modification Source: HGNC
  • protein initiator methionine removal Source: UniProtKB-HAMAP
  • protein processing Source: HGNC
  • regulation of rhodopsin mediated signaling pathway Source: Reactome
Complete GO annotation...

Keywords - Molecular functioni

Aminopeptidase, Hydrolase, Protease

Keywords - Ligandi

Metal-binding

Enzyme and pathway databases

BioCyciZFISH:HS03371-MONOMER.
BRENDAi3.4.11.18. 2681.
ReactomeiR-HSA-2514859. Inactivation, recovery and regulation of the phototransduction cascade.

Protein family/group databases

MEROPSiM24.002.

Names & Taxonomyi

Protein namesi
Recommended name:
Methionine aminopeptidase 2UniRule annotation (EC:3.4.11.18UniRule annotation)
Short name:
MAP 2UniRule annotation
Short name:
MetAP 2UniRule annotation
Alternative name(s):
Initiation factor 2-associated 67 kDa glycoproteinUniRule annotation
Short name:
p67UniRule annotation
Short name:
p67eIF2UniRule annotation
Peptidase MUniRule annotation
Gene namesi
Name:METAP2UniRule annotation
Synonyms:MNPEP, P67EIF2
OrganismiHomo sapiens (Human)
Taxonomic identifieri9606 [NCBI]
Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaEuarchontogliresPrimatesHaplorrhiniCatarrhiniHominidaeHomo
Proteomesi
  • UP000005640 Componenti: Chromosome 12

Organism-specific databases

HGNCiHGNC:16672. METAP2.

Subcellular locationi

  • Cytoplasm UniRule annotation1 Publication

  • Note: About 30% of expressed METAP2 associates with polysomes.

GO - Cellular componenti

  • cytoplasm Source: HGNC
  • cytosol Source: Reactome
  • plasma membrane Source: HPA
Complete GO annotation...

Keywords - Cellular componenti

Cytoplasm

Pathology & Biotechi

Organism-specific databases

DisGeNETi10988.
OpenTargetsiENSG00000111142.
PharmGKBiPA30765.

Chemistry databases

ChEMBLiCHEMBL3922.
DrugBankiDB00134. L-Methionine.
DB01422. Nitroxoline.
GuidetoPHARMACOLOGYi1573.

Polymorphism and mutation databases

BioMutaiMETAP2.
DMDMi1703273.

PTM / Processingi

Molecule processing

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Initiator methionineiRemovedCombined sources
ChainiPRO_00001489822 – 478Methionine aminopeptidase 2Add BLAST477

Amino acid modifications

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Modified residuei2N-acetylalanineCombined sources1
Modified residuei45PhosphoserineCombined sources1
Modified residuei60Phosphoserine; alternateCombined sources1
Glycosylationi60O-linked (GlcNAc); alternateBy similarity1
Modified residuei63Phosphoserine; alternateCombined sources1
Glycosylationi63O-linked (GlcNAc); alternateBy similarity1
Modified residuei74PhosphoserineCombined sources1

Post-translational modificationi

Contains approximately 12 O-linked N-acetylglucosamine (GlcNAc) residues. O-glycosylation is required for EIF2S1 binding.UniRule annotation1 Publication

Keywords - PTMi

Acetylation, Glycoprotein, Phosphoprotein

Proteomic databases

EPDiP50579.
MaxQBiP50579.
PaxDbiP50579.
PeptideAtlasiP50579.
PRIDEiP50579.
TopDownProteomicsiP50579-1. [P50579-1]

2D gel databases

REPRODUCTION-2DPAGEIPI00033036.

PTM databases

iPTMnetiP50579.
PhosphoSitePlusiP50579.
SwissPalmiP50579.

Expressioni

Gene expression databases

BgeeiENSG00000111142.
CleanExiHS_METAP2.
ExpressionAtlasiP50579. baseline and differential.
GenevisibleiP50579. HS.

Organism-specific databases

HPAiCAB013025.
HPA019095.

Interactioni

Subunit structurei

Interacts strongly with the eIF-2 gamma-subunit EIF2S3 (By similarity). Binds EIF2S1 at low magnesium concentrations.By similarity6 Publications

Protein-protein interaction databases

BioGridi116184. 45 interactors.
IntActiP50579. 4 interactors.
MINTiMINT-2803706.
STRINGi9606.ENSP00000325312.

Chemistry databases

BindingDBiP50579.

Structurei

Secondary structure

1478
Legend: HelixTurnBeta strandPDB Structure known for this area
Show more details
Feature keyPosition(s)DescriptionActionsGraphical viewLength
Helixi120 – 123Combined sources4
Beta strandi133 – 135Combined sources3
Beta strandi141 – 143Combined sources3
Helixi147 – 151Combined sources5
Helixi153 – 160Combined sources8
Helixi163 – 186Combined sources24
Helixi193 – 208Combined sources16
Helixi212 – 214Combined sources3
Beta strandi215 – 225Combined sources11
Beta strandi228 – 231Combined sources4
Beta strandi248 – 256Combined sources9
Beta strandi259 – 267Combined sources9
Helixi271 – 273Combined sources3
Helixi274 – 290Combined sources17
Helixi297 – 309Combined sources13
Beta strandi312 – 315Combined sources4
Beta strandi318 – 321Combined sources4
Beta strandi330 – 334Combined sources5
Beta strandi337 – 339Combined sources3
Beta strandi346 – 349Combined sources4
Beta strandi360 – 370Combined sources11
Beta strandi382 – 385Combined sources4
Helixi397 – 409Combined sources13
Turni410 – 412Combined sources3
Helixi417 – 421Combined sources5
Turni422 – 424Combined sources3
Helixi429 – 437Combined sources9
Beta strandi440 – 444Combined sources5
Beta strandi455 – 464Combined sources10
Beta strandi469 – 471Combined sources3

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
PDB entryMethodResolution (Å)ChainPositionsPDBsum
1B59X-ray1.80A109-478[»]
1B6AX-ray1.60A1-478[»]
1BN5X-ray1.80A1-478[»]
1BOAX-ray1.80A1-478[»]
1KQ0X-ray2.00A1-478[»]
1KQ9X-ray1.90A1-478[»]
1QZYX-ray1.60A1-478[»]
1R58X-ray1.90A110-478[»]
1R5GX-ray2.00A110-478[»]
1R5HX-ray2.40A110-478[»]
1YW7X-ray1.85A110-478[»]
1YW8X-ray2.65A110-478[»]
1YW9X-ray1.64A110-478[»]
2ADUX-ray1.90A110-478[»]
2EA2X-ray2.50A110-478[»]
2EA4X-ray2.35A110-478[»]
2GA2X-ray1.95A110-478[»]
2OAZX-ray1.90A110-478[»]
5CLSX-ray1.75A108-478[»]
5D6EX-ray1.49A108-478[»]
5D6FX-ray1.55A108-478[»]
5JFRX-ray1.60A110-478[»]
5JHUX-ray1.80A110-478[»]
5JI6X-ray2.15A110-478[»]
ProteinModelPortaliP50579.
SMRiP50579.
ModBaseiSearch...
MobiDBiSearch...

Miscellaneous databases

EvolutionaryTraceiP50579.

Family & Domainsi

Compositional bias

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Compositional biasi41 – 46Poly-Lys6
Compositional biasi98 – 106Poly-Lys9

Sequence similaritiesi

Belongs to the peptidase M24A family. Methionine aminopeptidase eukaryotic type 2 subfamily.UniRule annotation

Phylogenomic databases

eggNOGiKOG2775. Eukaryota.
COG0024. LUCA.
GeneTreeiENSGT00530000063220.
HOGENOMiHOG000226278.
HOVERGENiHBG050495.
InParanoidiP50579.
KOiK01265.
OMAiWEHTILL.
OrthoDBiEOG091G07WE.
PhylomeDBiP50579.
TreeFamiTF300426.

Family and domain databases

CDDicd01088. MetAP2. 1 hit.
Gene3Di1.10.10.10. 1 hit.
3.90.230.10. 2 hits.
HAMAPiMF_03175. MetAP_2_euk. 1 hit.
InterProiIPR000994. Pept_M24.
IPR001714. Pept_M24_MAP.
IPR002468. Pept_M24A_MAP2.
IPR018349. Pept_M24A_MAP2_BS.
IPR011991. WHTH_DNA-bd_dom.
[Graphical view]
PANTHERiPTHR10804:SF9. PTHR10804:SF9. 1 hit.
PfamiPF00557. Peptidase_M24. 1 hit.
[Graphical view]
PRINTSiPR00599. MAPEPTIDASE.
SUPFAMiSSF46785. SSF46785. 1 hit.
SSF55920. SSF55920. 2 hits.
TIGRFAMsiTIGR00501. met_pdase_II. 1 hit.
PROSITEiPS01202. MAP_2. 1 hit.
[Graphical view]

Sequences (3)i

Sequence statusi: Complete.

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

This entry describes 3 isoformsi produced by alternative splicing. AlignAdd to basket

Isoform 1 (identifier: P50579-1) [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
MAGVEEVAAS GSHLNGDLDP DDREEGAAST AEEAAKKKRR KKKKSKGPSA
60 70 80 90 100
AGEQEPDKES GASVDEVARQ LERSALEDKE RDEDDEDGDG DGDGATGKKK
110 120 130 140 150
KKKKKKRGPK VQTDPPSVPI CDLYPNGVFP KGQECEYPPT QDGRTAAWRT
160 170 180 190 200
TSEEKKALDQ ASEEIWNDFR EAAEAHRQVR KYVMSWIKPG MTMIEICEKL
210 220 230 240 250
EDCSRKLIKE NGLNAGLAFP TGCSLNNCAA HYTPNAGDTT VLQYDDICKI
260 270 280 290 300
DFGTHISGRI IDCAFTVTFN PKYDTLLKAV KDATNTGIKC AGIDVRLCDV
310 320 330 340 350
GEAIQEVMES YEVEIDGKTY QVKPIRNLNG HSIGQYRIHA GKTVPIVKGG
360 370 380 390 400
EATRMEEGEV YAIETFGSTG KGVVHDDMEC SHYMKNFDVG HVPIRLPRTK
410 420 430 440 450
HLLNVINENF GTLAFCRRWL DRLGESKYLM ALKNLCDLGI VDPYPPLCDI
460 470
KGSYTAQFEH TILLRPTCKE VVSRGDDY
Length:478
Mass (Da):52,892
Last modified:October 1, 1996 - v1
Checksum:i5788E4BB83E48F9A
GO
Isoform 2 (identifier: P50579-2) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     50-50: Missing.
     87-109: DGDGDGDGATGKKKKKKKKKRGP → A

Note: No experimental confirmation available.
Show »
Length:455
Mass (Da):50,510
Checksum:i6B2C99F5B40B951F
GO
Isoform 3 (identifier: P50579-3) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     109-132: PKVQTDPPSVPICDLYPNGVFPKG → R

Note: No experimental confirmation available.
Show »
Length:455
Mass (Da):50,497
Checksum:i7370E721E31AAD64
GO

Experimental Info

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Sequence conflicti434N → D in BAC03733 (PubMed:14702039).Curated1

Alternative sequence

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Alternative sequenceiVSP_05546750Missing in isoform 2. 1 Publication1
Alternative sequenceiVSP_05546887 – 109DGDGD…KKRGP → A in isoform 2. 1 PublicationAdd BLAST23
Alternative sequenceiVSP_057353109 – 132PKVQT…VFPKG → R in isoform 3. 1 PublicationAdd BLAST24

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
U29607 mRNA. Translation: AAA82930.1.
U13261 mRNA. Translation: AAC63402.1.
AK091730 mRNA. Translation: BAC03733.1.
AK300836 mRNA. Translation: BAG62487.1.
AK315559 mRNA. Translation: BAG37935.1.
AC018475 Genomic DNA. No translation available.
CH471054 Genomic DNA. Translation: EAW97537.1.
CH471054 Genomic DNA. Translation: EAW97538.1.
BC013782 mRNA. Translation: AAH13782.1.
CCDSiCCDS81723.1. [P50579-3]
CCDS81725.1. [P50579-2]
CCDS9052.1. [P50579-1]
PIRiS52112. DPHUM2.
RefSeqiNP_001304111.1. NM_001317182.1. [P50579-3]
NP_001304112.1. NM_001317183.1. [P50579-2]
NP_001317175.1. NM_001330246.1.
NP_006829.1. NM_006838.3. [P50579-1]
UniGeneiHs.444986.

Genome annotation databases

EnsembliENST00000261220; ENSP00000261220; ENSG00000111142. [P50579-2]
ENST00000323666; ENSP00000325312; ENSG00000111142. [P50579-1]
ENST00000546753; ENSP00000448169; ENSG00000111142. [P50579-3]
GeneIDi10988.
KEGGihsa:10988.
UCSCiuc001tec.4. human. [P50579-1]

Keywords - Coding sequence diversityi

Alternative splicing

Cross-referencesi

Web resourcesi

Atlas of Genetics and Cytogenetics in Oncology and Haematology

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
U29607 mRNA. Translation: AAA82930.1.
U13261 mRNA. Translation: AAC63402.1.
AK091730 mRNA. Translation: BAC03733.1.
AK300836 mRNA. Translation: BAG62487.1.
AK315559 mRNA. Translation: BAG37935.1.
AC018475 Genomic DNA. No translation available.
CH471054 Genomic DNA. Translation: EAW97537.1.
CH471054 Genomic DNA. Translation: EAW97538.1.
BC013782 mRNA. Translation: AAH13782.1.
CCDSiCCDS81723.1. [P50579-3]
CCDS81725.1. [P50579-2]
CCDS9052.1. [P50579-1]
PIRiS52112. DPHUM2.
RefSeqiNP_001304111.1. NM_001317182.1. [P50579-3]
NP_001304112.1. NM_001317183.1. [P50579-2]
NP_001317175.1. NM_001330246.1.
NP_006829.1. NM_006838.3. [P50579-1]
UniGeneiHs.444986.

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
PDB entryMethodResolution (Å)ChainPositionsPDBsum
1B59X-ray1.80A109-478[»]
1B6AX-ray1.60A1-478[»]
1BN5X-ray1.80A1-478[»]
1BOAX-ray1.80A1-478[»]
1KQ0X-ray2.00A1-478[»]
1KQ9X-ray1.90A1-478[»]
1QZYX-ray1.60A1-478[»]
1R58X-ray1.90A110-478[»]
1R5GX-ray2.00A110-478[»]
1R5HX-ray2.40A110-478[»]
1YW7X-ray1.85A110-478[»]
1YW8X-ray2.65A110-478[»]
1YW9X-ray1.64A110-478[»]
2ADUX-ray1.90A110-478[»]
2EA2X-ray2.50A110-478[»]
2EA4X-ray2.35A110-478[»]
2GA2X-ray1.95A110-478[»]
2OAZX-ray1.90A110-478[»]
5CLSX-ray1.75A108-478[»]
5D6EX-ray1.49A108-478[»]
5D6FX-ray1.55A108-478[»]
5JFRX-ray1.60A110-478[»]
5JHUX-ray1.80A110-478[»]
5JI6X-ray2.15A110-478[»]
ProteinModelPortaliP50579.
SMRiP50579.
ModBaseiSearch...
MobiDBiSearch...

Protein-protein interaction databases

BioGridi116184. 45 interactors.
IntActiP50579. 4 interactors.
MINTiMINT-2803706.
STRINGi9606.ENSP00000325312.

Chemistry databases

BindingDBiP50579.
ChEMBLiCHEMBL3922.
DrugBankiDB00134. L-Methionine.
DB01422. Nitroxoline.
GuidetoPHARMACOLOGYi1573.

Protein family/group databases

MEROPSiM24.002.

PTM databases

iPTMnetiP50579.
PhosphoSitePlusiP50579.
SwissPalmiP50579.

Polymorphism and mutation databases

BioMutaiMETAP2.
DMDMi1703273.

2D gel databases

REPRODUCTION-2DPAGEIPI00033036.

Proteomic databases

EPDiP50579.
MaxQBiP50579.
PaxDbiP50579.
PeptideAtlasiP50579.
PRIDEiP50579.
TopDownProteomicsiP50579-1. [P50579-1]

Protocols and materials databases

DNASUi10988.
Structural Biology KnowledgebaseSearch...

Genome annotation databases

EnsembliENST00000261220; ENSP00000261220; ENSG00000111142. [P50579-2]
ENST00000323666; ENSP00000325312; ENSG00000111142. [P50579-1]
ENST00000546753; ENSP00000448169; ENSG00000111142. [P50579-3]
GeneIDi10988.
KEGGihsa:10988.
UCSCiuc001tec.4. human. [P50579-1]

Organism-specific databases

CTDi10988.
DisGeNETi10988.
GeneCardsiMETAP2.
HGNCiHGNC:16672. METAP2.
HPAiCAB013025.
HPA019095.
MIMi601870. gene.
neXtProtiNX_P50579.
OpenTargetsiENSG00000111142.
PharmGKBiPA30765.
GenAtlasiSearch...

Phylogenomic databases

eggNOGiKOG2775. Eukaryota.
COG0024. LUCA.
GeneTreeiENSGT00530000063220.
HOGENOMiHOG000226278.
HOVERGENiHBG050495.
InParanoidiP50579.
KOiK01265.
OMAiWEHTILL.
OrthoDBiEOG091G07WE.
PhylomeDBiP50579.
TreeFamiTF300426.

Enzyme and pathway databases

BioCyciZFISH:HS03371-MONOMER.
BRENDAi3.4.11.18. 2681.
ReactomeiR-HSA-2514859. Inactivation, recovery and regulation of the phototransduction cascade.

Miscellaneous databases

ChiTaRSiMETAP2. human.
EvolutionaryTraceiP50579.
GeneWikiiMETAP2.
GenomeRNAii10988.
PROiP50579.
SOURCEiSearch...

Gene expression databases

BgeeiENSG00000111142.
CleanExiHS_METAP2.
ExpressionAtlasiP50579. baseline and differential.
GenevisibleiP50579. HS.

Family and domain databases

CDDicd01088. MetAP2. 1 hit.
Gene3Di1.10.10.10. 1 hit.
3.90.230.10. 2 hits.
HAMAPiMF_03175. MetAP_2_euk. 1 hit.
InterProiIPR000994. Pept_M24.
IPR001714. Pept_M24_MAP.
IPR002468. Pept_M24A_MAP2.
IPR018349. Pept_M24A_MAP2_BS.
IPR011991. WHTH_DNA-bd_dom.
[Graphical view]
PANTHERiPTHR10804:SF9. PTHR10804:SF9. 1 hit.
PfamiPF00557. Peptidase_M24. 1 hit.
[Graphical view]
PRINTSiPR00599. MAPEPTIDASE.
SUPFAMiSSF46785. SSF46785. 1 hit.
SSF55920. SSF55920. 2 hits.
TIGRFAMsiTIGR00501. met_pdase_II. 1 hit.
PROSITEiPS01202. MAP_2. 1 hit.
[Graphical view]
ProtoNetiSearch...

Entry informationi

Entry nameiMAP2_HUMAN
AccessioniPrimary (citable) accession number: P50579
Secondary accession number(s): B2RDI8
, B4DUX5, G3XA91, Q8NB11
Entry historyi
Integrated into UniProtKB/Swiss-Prot: October 1, 1996
Last sequence update: October 1, 1996
Last modified: November 30, 2016
This is version 172 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, Direct protein sequencing, Reference proteome

Documents

  1. Human chromosome 12
    Human chromosome 12: entries, gene names and cross-references to MIM
  2. MIM cross-references
    Online Mendelian Inheritance in Man (MIM) cross-references in UniProtKB/Swiss-Prot
  3. PDB cross-references
    Index of Protein Data Bank (PDB) cross-references
  4. Peptidase families
    Classification of peptidase families and list of entries
  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.