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Protein

Proteasome activator complex subunit 3

Gene

PSME3

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

Functioni

Subunit of the 11S REG-gamma (also called PA28-gamma) proteasome regulator, a doughnut-shaped homoheptamer which associates with the proteasome. 11S REG-gamma activates the trypsin-like catalytic subunit of the proteasome but inhibits the chymotrypsin-like and postglutamyl-preferring (PGPH) subunits. Facilitates the MDM2-p53/TP53 interaction which promotes ubiquitination- and MDM2-dependent proteasomal degradation of p53/TP53, limiting its accumulation and resulting in inhibited apoptosis after DNA damage. May also be involved in cell cycle regulation. Mediates CCAR2 and CHEK2-dependent SIRT1 inhibition (PubMed:25361978).7 Publications

GO - Molecular functioni

  • endopeptidase activator activity Source: UniProtKB
  • identical protein binding Source: IntAct
  • MDM2/MDM4 family protein binding Source: UniProtKB
  • p53 binding Source: UniProtKB

GO - Biological processi

Complete GO annotation...

Keywords - Biological processi

Apoptosis, Cell cycle

Enzyme and pathway databases

BioCyciZFISH:ENSG00000131467-MONOMER.
ReactomeiR-HSA-1169091. Activation of NF-kappaB in B cells.
R-HSA-1234176. Oxygen-dependent proline hydroxylation of Hypoxia-inducible Factor Alpha.
R-HSA-1236974. ER-Phagosome pathway.
R-HSA-1236978. Cross-presentation of soluble exogenous antigens (endosomes).
R-HSA-174084. Autodegradation of Cdh1 by Cdh1:APC/C.
R-HSA-174113. SCF-beta-TrCP mediated degradation of Emi1.
R-HSA-174154. APC/C:Cdc20 mediated degradation of Securin.
R-HSA-174178. APC/C:Cdh1 mediated degradation of Cdc20 and other APC/C:Cdh1 targeted proteins in late mitosis/early G1.
R-HSA-174184. Cdc20:Phospho-APC/C mediated degradation of Cyclin A.
R-HSA-180534. Vpu mediated degradation of CD4.
R-HSA-180585. Vif-mediated degradation of APOBEC3G.
R-HSA-187577. SCF(Skp2)-mediated degradation of p27/p21.
R-HSA-195253. Degradation of beta-catenin by the destruction complex.
R-HSA-202424. Downstream TCR signaling.
R-HSA-211733. Regulation of activated PAK-2p34 by proteasome mediated degradation.
R-HSA-2467813. Separation of Sister Chromatids.
R-HSA-2871837. FCERI mediated NF-kB activation.
R-HSA-349425. Autodegradation of the E3 ubiquitin ligase COP1.
R-HSA-350562. Regulation of ornithine decarboxylase (ODC).
R-HSA-382556. ABC-family proteins mediated transport.
R-HSA-450408. AUF1 (hnRNP D0) binds and destabilizes mRNA.
R-HSA-4608870. Asymmetric localization of PCP proteins.
R-HSA-4641257. Degradation of AXIN.
R-HSA-4641258. Degradation of DVL.
R-HSA-5358346. Hedgehog ligand biogenesis.
R-HSA-5362768. Hh mutants that don't undergo autocatalytic processing are degraded by ERAD.
R-HSA-5607761. Dectin-1 mediated noncanonical NF-kB signaling.
R-HSA-5607764. CLEC7A (Dectin-1) signaling.
R-HSA-5610780. Degradation of GLI1 by the proteasome.
R-HSA-5610783. Degradation of GLI2 by the proteasome.
R-HSA-5610785. GLI3 is processed to GLI3R by the proteasome.
R-HSA-5632684. Hedgehog 'on' state.
R-HSA-5658442. Regulation of RAS by GAPs.
R-HSA-5668541. TNFR2 non-canonical NF-kB pathway.
R-HSA-5676590. NIK-->noncanonical NF-kB signaling.
R-HSA-5678895. Defective CFTR causes cystic fibrosis.
R-HSA-5687128. MAPK6/MAPK4 signaling.
R-HSA-5689603. UCH proteinases.
R-HSA-5689880. Ub-specific processing proteases.
R-HSA-68827. CDT1 association with the CDC6:ORC:origin complex.
R-HSA-68949. Orc1 removal from chromatin.
R-HSA-69017. CDK-mediated phosphorylation and removal of Cdc6.
R-HSA-69229. Ubiquitin-dependent degradation of Cyclin D1.
R-HSA-69481. G2/M Checkpoints.
R-HSA-69601. Ubiquitin Mediated Degradation of Phosphorylated Cdc25A.
R-HSA-8852276. The role of GTSE1 in G2/M progression after G2 checkpoint.
R-HSA-8854050. FBXL7 down-regulates AURKA during mitotic entry and in early mitosis.
R-HSA-983168. Antigen processing: Ubiquitination & Proteasome degradation.

Names & Taxonomyi

Protein namesi
Recommended name:
Proteasome activator complex subunit 3
Alternative name(s):
11S regulator complex subunit gamma
Short name:
REG-gamma
Activator of multicatalytic protease subunit 3
Ki nuclear autoantigen
Proteasome activator 28 subunit gamma
Short name:
PA28g
Short name:
PA28gamma
Gene namesi
Name:PSME3
OrganismiHomo sapiens (Human)
Taxonomic identifieri9606 [NCBI]
Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaEuarchontogliresPrimatesHaplorrhiniCatarrhiniHominidaeHomo
Proteomesi
  • UP000005640 Componenti: Chromosome 17

Organism-specific databases

HGNCiHGNC:9570. PSME3.

Subcellular locationi

GO - Cellular componenti

  • cytoplasm Source: HPA
  • cytosol Source: Reactome
  • membrane Source: UniProtKB
  • nucleoplasm Source: HPA
  • nucleus Source: UniProtKB
  • proteasome activator complex Source: InterPro
  • proteasome complex Source: ProtInc
Complete GO annotation...

Keywords - Cellular componenti

Cytoplasm, Nucleus, Proteasome

Pathology & Biotechi

Mutagenesis

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Mutagenesisi188K → E, D, A, C, N, Q, H, F, S, I or P: Assembles into less stable hexamers/heptamers and therefore impairs specificity of activation of trypsin-like subunits of the proteasome. 1 Publication1

Organism-specific databases

DisGeNETi10197.
OpenTargetsiENSG00000131467.
PharmGKBiPA33916.

Polymorphism and mutation databases

BioMutaiPSME3.
DMDMi47117724.

PTM / Processingi

Molecule processing

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Initiator methionineiRemovedCombined sources1 Publication
ChainiPRO_00001617892 – 254Proteasome activator complex subunit 3Add BLAST253

Amino acid modifications

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Modified residuei2N-acetylalanineCombined sources1 Publication1
Modified residuei17PhosphoserineCombined sources1
Modified residuei24PhosphoserineCombined sources1
Modified residuei195N6-acetyllysine; by P300/CBP1 Publication1
Modified residuei247Phosphoserine; by CHEK21 Publication1

Post-translational modificationi

Phosphorylated by MAP3K3 (By similarity). Phosphorylation at Ser-247 promotes its association with CCAR2.By similarity1 Publication
Acetylation at the major site Lys-195 is important for oligomerization and ability to degrade its target substrates. Deacetylated by SIRT1.2 Publications

Keywords - PTMi

Acetylation, Phosphoprotein

Proteomic databases

EPDiP61289.
PaxDbiP61289.
PeptideAtlasiP61289.
PRIDEiP61289.

PTM databases

iPTMnetiP61289.
PhosphoSitePlusiP61289.
SwissPalmiP61289.

Miscellaneous databases

PMAP-CutDBP61289.

Expressioni

Inductioni

Up-regulated in thyroid carcinoma cells.1 Publication

Gene expression databases

BgeeiENSG00000131467.
CleanExiHS_PSME3.
ExpressionAtlasiP61289. baseline and differential.
GenevisibleiP61289. HS.

Organism-specific databases

HPAiCAB008388.
HPA012510.

Interactioni

Subunit structurei

Homoheptamer; the stability of the heptamer is essential for the specific activation of the trypsine-like subunit and inhibition of the chymotrypsin-like and postglutamyl-preferring (PGPH) subunits of the proteasome. Interacts with p53/TP53 and MDM2. Interacts with MAP3K3 (By similarity). Associates with the proteasome. Interacts with human cytomegalovirus UL27. Interacts with CCAR2.By similarity8 Publications

Binary interactionsi

WithEntry#Exp.IntActNotes
itself7EBI-355546,EBI-355546
O9307711EBI-355546,EBI-9636511From a different organism.
ATN1P542593EBI-355546,EBI-945980
BBS2Q9BXC94EBI-355546,EBI-748297
COILP384325EBI-355546,EBI-945751
DIP2AQ14689-63EBI-355546,EBI-10233719
EAF1Q96JC98EBI-355546,EBI-769261
EAF2Q96CJ13EBI-355546,EBI-1245604
FBXO7Q9Y3I13EBI-355546,EBI-1161222
MDM2Q009878EBI-355546,EBI-389668
NCOA3Q9Y6Q95EBI-355546,EBI-81196
PFDN5Q994715EBI-355546,EBI-357275
PRKAB2O437417EBI-355546,EBI-1053424
PRR13Q9NZ815EBI-355546,EBI-740924
SMURF1Q9HCE75EBI-355546,EBI-976466
SPG7Q9UQ903EBI-355546,EBI-717201
TNFAIP8L1Q8WVP55EBI-355546,EBI-752102
TP53P046377EBI-355546,EBI-366083
TXN2Q997573EBI-355546,EBI-2932492
vifP125042EBI-355546,EBI-779991From a different organism.
WDYHV1Q96HA84EBI-355546,EBI-741158
ZCCHC10Q8TBK66EBI-355546,EBI-597063

GO - Molecular functioni

  • identical protein binding Source: IntAct
  • MDM2/MDM4 family protein binding Source: UniProtKB
  • p53 binding Source: UniProtKB

Protein-protein interaction databases

BioGridi115492. 172 interactors.
IntActiP61289. 82 interactors.
MINTiMINT-5002653.
STRINGi9606.ENSP00000293362.

Structurei

3D structure databases

ProteinModelPortaliP61289.
SMRiP61289.
ModBaseiSearch...
MobiDBiSearch...

Family & Domainsi

Domaini

The C-terminal sequences affect heptamer stability and proteasome affinity.1 Publication

Sequence similaritiesi

Belongs to the PA28 family.Curated

Phylogenomic databases

eggNOGiKOG4470. Eukaryota.
ENOG410XQVX. LUCA.
GeneTreeiENSGT00510000046374.
HOVERGENiHBG053745.
InParanoidiP61289.
KOiK06698.
OMAiPCNKPLC.
OrthoDBiEOG091G0GX7.
PhylomeDBiP61289.
TreeFamiTF106236.

Family and domain databases

Gene3Di1.20.120.180. 1 hit.
1.20.5.120. 1 hit.
InterProiIPR009077. Proteasome_activ_pa28.
IPR003186. Proteasome_activ_pa28_C.
IPR003185. Proteasome_activ_pa28_N.
[Graphical view]
PANTHERiPTHR10660. PTHR10660. 1 hit.
PfamiPF02251. PA28_alpha. 1 hit.
PF02252. PA28_beta. 1 hit.
[Graphical view]
SUPFAMiSSF47216. SSF47216. 2 hits.

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: P61289-1) [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
MASLLKVDQE VKLKVDSFRE RITSEAEDLV ANFFPKKLLE LDSFLKEPIL
60 70 80 90 100
NIHDLTQIHS DMNLPVPDPI LLTNSHDGLD GPTYKKRRLD ECEEAFQGTK
110 120 130 140 150
VFVMPNGMLK SNQQLVDIIE KVKPEIRLLI EKCNTVKMWV QLLIPRIEDG
160 170 180 190 200
NNFGVSIQEE TVAELRTVES EAASYLDQIS RYYITRAKLV SKIAKYPHVE
210 220 230 240 250
DYRRTVTEID EKEYISLRLI ISELRNQYVT LHDMILKNIE KIKRPRSSNA

ETLY
Length:254
Mass (Da):29,506
Last modified:May 10, 2004 - v1
Checksum:i116FAB47D60A26C0
GO
Isoform 2 (identifier: P61289-2) [UniParc] [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     135-135: T → TPSGKGPHICFDLQ

Show »
Length:267
Mass (Da):30,887
Checksum:i76E7E6ECCC65589F
GO
Isoform 3 (identifier: P61289-3) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     1-13: MASLLKVDQEVKL → MEKWILKKIKYLQSGGLSASYYSY

Note: No experimental confirmation. Gene prediction based on EST data.
Show »
Length:265
Mass (Da):30,890
Checksum:iEC200E4F73756C82
GO

Experimental Info

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Sequence conflicti25E → K in AAB60335 (PubMed:7951316).Curated1
Sequence conflicti94E → K in AAA93227 (PubMed:7545954).Curated1

Alternative sequence

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Alternative sequenceiVSP_0550471 – 13MASLL…QEVKL → MEKWILKKIKYLQSGGLSAS YYSY in isoform 3. CuratedAdd BLAST13
Alternative sequenceiVSP_004516135T → TPSGKGPHICFDLQ in isoform 2. 1 Publication1

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
U11292 mRNA. Translation: AAB60335.1.
BT019386 mRNA. Translation: AAV38193.1.
AK292618 mRNA. Translation: BAF85307.1.
AK074999 mRNA. Translation: BAG52046.1.
AC016889 Genomic DNA. No translation available.
CH471152 Genomic DNA. Translation: EAW60893.1.
BC001423 mRNA. Translation: AAH01423.1.
BC002684 mRNA. Translation: AAH02684.1.
BC008020 mRNA. Translation: AAH08020.1.
U25756 Genomic DNA. Translation: AAA93227.1.
CCDSiCCDS11442.1. [P61289-2]
CCDS45689.1.
CCDS59290.1. [P61289-3]
PIRiI38702. A60537.
RefSeqiNP_005780.2. NM_005789.3. [P61289-1]
NP_789839.1. NM_176863.2. [P61289-2]
UniGeneiHs.152978.

Genome annotation databases

EnsembliENST00000293362; ENSP00000293362; ENSG00000131467. [P61289-2]
ENST00000441946; ENSP00000409487; ENSG00000131467. [P61289-3]
ENST00000590720; ENSP00000466794; ENSG00000131467. [P61289-1]
GeneIDi10197.
KEGGihsa:10197.
UCSCiuc002ibq.5. human.

Keywords - Coding sequence diversityi

Alternative splicing

Cross-referencesi

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
U11292 mRNA. Translation: AAB60335.1.
BT019386 mRNA. Translation: AAV38193.1.
AK292618 mRNA. Translation: BAF85307.1.
AK074999 mRNA. Translation: BAG52046.1.
AC016889 Genomic DNA. No translation available.
CH471152 Genomic DNA. Translation: EAW60893.1.
BC001423 mRNA. Translation: AAH01423.1.
BC002684 mRNA. Translation: AAH02684.1.
BC008020 mRNA. Translation: AAH08020.1.
U25756 Genomic DNA. Translation: AAA93227.1.
CCDSiCCDS11442.1. [P61289-2]
CCDS45689.1.
CCDS59290.1. [P61289-3]
PIRiI38702. A60537.
RefSeqiNP_005780.2. NM_005789.3. [P61289-1]
NP_789839.1. NM_176863.2. [P61289-2]
UniGeneiHs.152978.

3D structure databases

ProteinModelPortaliP61289.
SMRiP61289.
ModBaseiSearch...
MobiDBiSearch...

Protein-protein interaction databases

BioGridi115492. 172 interactors.
IntActiP61289. 82 interactors.
MINTiMINT-5002653.
STRINGi9606.ENSP00000293362.

PTM databases

iPTMnetiP61289.
PhosphoSitePlusiP61289.
SwissPalmiP61289.

Polymorphism and mutation databases

BioMutaiPSME3.
DMDMi47117724.

Proteomic databases

EPDiP61289.
PaxDbiP61289.
PeptideAtlasiP61289.
PRIDEiP61289.

Protocols and materials databases

DNASUi10197.
Structural Biology KnowledgebaseSearch...

Genome annotation databases

EnsembliENST00000293362; ENSP00000293362; ENSG00000131467. [P61289-2]
ENST00000441946; ENSP00000409487; ENSG00000131467. [P61289-3]
ENST00000590720; ENSP00000466794; ENSG00000131467. [P61289-1]
GeneIDi10197.
KEGGihsa:10197.
UCSCiuc002ibq.5. human.

Organism-specific databases

CTDi10197.
DisGeNETi10197.
GeneCardsiPSME3.
HGNCiHGNC:9570. PSME3.
HPAiCAB008388.
HPA012510.
MIMi605129. gene.
neXtProtiNX_P61289.
OpenTargetsiENSG00000131467.
PharmGKBiPA33916.
GenAtlasiSearch...

Phylogenomic databases

eggNOGiKOG4470. Eukaryota.
ENOG410XQVX. LUCA.
GeneTreeiENSGT00510000046374.
HOVERGENiHBG053745.
InParanoidiP61289.
KOiK06698.
OMAiPCNKPLC.
OrthoDBiEOG091G0GX7.
PhylomeDBiP61289.
TreeFamiTF106236.

Enzyme and pathway databases

BioCyciZFISH:ENSG00000131467-MONOMER.
ReactomeiR-HSA-1169091. Activation of NF-kappaB in B cells.
R-HSA-1234176. Oxygen-dependent proline hydroxylation of Hypoxia-inducible Factor Alpha.
R-HSA-1236974. ER-Phagosome pathway.
R-HSA-1236978. Cross-presentation of soluble exogenous antigens (endosomes).
R-HSA-174084. Autodegradation of Cdh1 by Cdh1:APC/C.
R-HSA-174113. SCF-beta-TrCP mediated degradation of Emi1.
R-HSA-174154. APC/C:Cdc20 mediated degradation of Securin.
R-HSA-174178. APC/C:Cdh1 mediated degradation of Cdc20 and other APC/C:Cdh1 targeted proteins in late mitosis/early G1.
R-HSA-174184. Cdc20:Phospho-APC/C mediated degradation of Cyclin A.
R-HSA-180534. Vpu mediated degradation of CD4.
R-HSA-180585. Vif-mediated degradation of APOBEC3G.
R-HSA-187577. SCF(Skp2)-mediated degradation of p27/p21.
R-HSA-195253. Degradation of beta-catenin by the destruction complex.
R-HSA-202424. Downstream TCR signaling.
R-HSA-211733. Regulation of activated PAK-2p34 by proteasome mediated degradation.
R-HSA-2467813. Separation of Sister Chromatids.
R-HSA-2871837. FCERI mediated NF-kB activation.
R-HSA-349425. Autodegradation of the E3 ubiquitin ligase COP1.
R-HSA-350562. Regulation of ornithine decarboxylase (ODC).
R-HSA-382556. ABC-family proteins mediated transport.
R-HSA-450408. AUF1 (hnRNP D0) binds and destabilizes mRNA.
R-HSA-4608870. Asymmetric localization of PCP proteins.
R-HSA-4641257. Degradation of AXIN.
R-HSA-4641258. Degradation of DVL.
R-HSA-5358346. Hedgehog ligand biogenesis.
R-HSA-5362768. Hh mutants that don't undergo autocatalytic processing are degraded by ERAD.
R-HSA-5607761. Dectin-1 mediated noncanonical NF-kB signaling.
R-HSA-5607764. CLEC7A (Dectin-1) signaling.
R-HSA-5610780. Degradation of GLI1 by the proteasome.
R-HSA-5610783. Degradation of GLI2 by the proteasome.
R-HSA-5610785. GLI3 is processed to GLI3R by the proteasome.
R-HSA-5632684. Hedgehog 'on' state.
R-HSA-5658442. Regulation of RAS by GAPs.
R-HSA-5668541. TNFR2 non-canonical NF-kB pathway.
R-HSA-5676590. NIK-->noncanonical NF-kB signaling.
R-HSA-5678895. Defective CFTR causes cystic fibrosis.
R-HSA-5687128. MAPK6/MAPK4 signaling.
R-HSA-5689603. UCH proteinases.
R-HSA-5689880. Ub-specific processing proteases.
R-HSA-68827. CDT1 association with the CDC6:ORC:origin complex.
R-HSA-68949. Orc1 removal from chromatin.
R-HSA-69017. CDK-mediated phosphorylation and removal of Cdc6.
R-HSA-69229. Ubiquitin-dependent degradation of Cyclin D1.
R-HSA-69481. G2/M Checkpoints.
R-HSA-69601. Ubiquitin Mediated Degradation of Phosphorylated Cdc25A.
R-HSA-8852276. The role of GTSE1 in G2/M progression after G2 checkpoint.
R-HSA-8854050. FBXL7 down-regulates AURKA during mitotic entry and in early mitosis.
R-HSA-983168. Antigen processing: Ubiquitination & Proteasome degradation.

Miscellaneous databases

ChiTaRSiPSME3. human.
GeneWikiiPSME3.
GenomeRNAii10197.
PMAP-CutDBP61289.
PROiP61289.
SOURCEiSearch...

Gene expression databases

BgeeiENSG00000131467.
CleanExiHS_PSME3.
ExpressionAtlasiP61289. baseline and differential.
GenevisibleiP61289. HS.

Family and domain databases

Gene3Di1.20.120.180. 1 hit.
1.20.5.120. 1 hit.
InterProiIPR009077. Proteasome_activ_pa28.
IPR003186. Proteasome_activ_pa28_C.
IPR003185. Proteasome_activ_pa28_N.
[Graphical view]
PANTHERiPTHR10660. PTHR10660. 1 hit.
PfamiPF02251. PA28_alpha. 1 hit.
PF02252. PA28_beta. 1 hit.
[Graphical view]
SUPFAMiSSF47216. SSF47216. 2 hits.
ProtoNetiSearch...

Entry informationi

Entry nameiPSME3_HUMAN
AccessioniPrimary (citable) accession number: P61289
Secondary accession number(s): A8K9A3
, O35563, P97373, Q12920, Q13172, Q9BQD9
Entry historyi
Integrated into UniProtKB/Swiss-Prot: May 10, 2004
Last sequence update: May 10, 2004
Last modified: November 30, 2016
This is version 140 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, Direct protein sequencing, Reference proteome

Documents

  1. Human chromosome 17
    Human chromosome 17: 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. 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.