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Protein

ATPase 2, plasma membrane-type

Gene

AHA2

Organism
Arabidopsis thaliana (Mouse-ear cress)
Status
Reviewed-Annotation score: Annotation score: 5 out of 5-Experimental evidence at protein leveli

Functioni

The plasma membrane H+ ATPase of plants and fungi generates a proton gradient that drives the active transport of nutrients by H+-symport (PubMed:10748244, PubMed:12920605, PubMed:27013734). The resulting external acidification and/or internal alkinization may mediate growth responses (PubMed:10748244, PubMed:12920605). Involved in maintaining the membrane potential and delta-pH, together forming the plasma membrane protonmotive force (PMF) required for root and hypocotyl elongation and root tropism (PubMed:22214817, PubMed:24492258). Important for root growth and development during different nitrogen regimes (PubMed:25382626). Forms a functional cation-translocating unit with CNGC17 that is activated by PSKR1/BAK1 and possibly other BAK1/RLK complexes (PubMed:26071421).1 Publication6 Publications

Catalytic activityi

ATP + H2O + H+(In) = ADP + phosphate + H+(Out).Curated

Enzyme regulationi

Regulated by an auto-inhibitory C-terminal domain that can be displaced by phosphorylation of Thr-947 and the subsequent binding of 14-3-3 proteins (PubMed:10353834). Negatively regulated by PKS5 (PubMed:17483306). PKS5 phosphorylates Ser-931, inhibiting interaction with the activating 14-3-3 protein (PubMed:17483306). Positively regulated by PSY1R (PubMed:25267325). PSY1R phosphorylates Thr-881, situated in the auto-inhibitory region I of the C-terminal domain, causing pump activation (PubMed:25267325). Negatively regulated by the secreted peptide RALF (PubMed:24458638). After specific binding to FERONIA, RALF causes phosphorylation at Ser-899, mediating the inhibition of proton transport (PubMed:24458638). Activated by lysophospholipids, without the involvment of phosphorylation of Thr-947 (PubMed:25971968). This activation is critically dependent on the single autoinhibitory residue Leu-919 (PubMed:25971968).6 Publications

Kineticsi

  1. KM=1.2 mM for ATP1 Publication
  1. Vmax=0.87 µmol/min/mg enzyme1 Publication

Sites

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Active sitei329 – 32914-aspartylphosphate intermediateBy similarity
Metal bindingi588 – 5881MagnesiumBy similarity
Metal bindingi592 – 5921MagnesiumBy similarity

GO - Molecular functioni

  • ATP binding Source: UniProtKB-KW
  • hydrogen-exporting ATPase activity, phosphorylative mechanism Source: UniProtKB
  • magnesium ion binding Source: UniProtKB

GO - Biological processi

Complete GO annotation...

Keywords - Molecular functioni

Hydrolase

Keywords - Biological processi

Hydrogen ion transport, Ion transport, Transport

Keywords - Ligandi

ATP-binding, Magnesium, Metal-binding, Nucleotide-binding

Enzyme and pathway databases

BioCyciARA:AT4G30190-MONOMER.
ARA:GQT-365-MONOMER.
BRENDAi3.6.3.6. 399.
SABIO-RKP19456.

Protein family/group databases

TCDBi3.A.3.3.9. the p-type atpase (p-atpase) superfamily.

Names & Taxonomyi

Protein namesi
Recommended name:
ATPase 2, plasma membrane-type1 Publication (EC:3.6.3.6Curated)
Alternative name(s):
Proton pump 2
Gene namesi
Name:AHA21 Publication
Ordered Locus Names:At4g30190Imported
ORF Names:F9N11.40Imported
OrganismiArabidopsis thaliana (Mouse-ear cress)
Taxonomic identifieri3702 [NCBI]
Taxonomic lineageiEukaryotaViridiplantaeStreptophytaEmbryophytaTracheophytaSpermatophytaMagnoliophytaeudicotyledonsGunneridaePentapetalaerosidsmalvidsBrassicalesBrassicaceaeCamelineaeArabidopsis
Proteomesi
  • UP000006548 Componenti: Chromosome 4

Organism-specific databases

TAIRiAT4G30190.

Subcellular locationi

Topology

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Topological domaini2 – 6160CytoplasmicSequence analysisAdd
BLAST
Transmembranei62 – 8120Helical; Name=1Sequence analysisAdd
BLAST
Topological domaini82 – 9312ExtracellularSequence analysisAdd
BLAST
Transmembranei94 – 11421Helical; Name=2Sequence analysisAdd
BLAST
Topological domaini115 – 243129CytoplasmicSequence analysisAdd
BLAST
Transmembranei244 – 26421Helical; Name=3Sequence analysisAdd
BLAST
Topological domaini265 – 2739ExtracellularSequence analysis
Transmembranei274 – 29118Helical; Name=4Sequence analysisAdd
BLAST
Topological domaini292 – 643352CytoplasmicSequence analysisAdd
BLAST
Transmembranei644 – 66522Helical; Name=5Sequence analysisAdd
BLAST
Topological domaini666 – 6705ExtracellularSequence analysis
Transmembranei671 – 69323Helical; Name=6Sequence analysisAdd
BLAST
Topological domaini694 – 70916CytoplasmicSequence analysisAdd
BLAST
Transmembranei710 – 73021Helical; Name=7Sequence analysisAdd
BLAST
Topological domaini731 – 75121ExtracellularSequence analysisAdd
BLAST
Transmembranei752 – 77221Helical; Name=8Sequence analysisAdd
BLAST
Topological domaini773 – 78412CytoplasmicSequence analysisAdd
BLAST
Transmembranei785 – 80521Helical; Name=9Sequence analysisAdd
BLAST
Topological domaini806 – 8138ExtracellularSequence analysis
Transmembranei814 – 83421Helical; Name=10Sequence analysisAdd
BLAST
Topological domaini835 – 948114CytoplasmicSequence analysisAdd
BLAST

GO - Cellular componenti

  • integral component of membrane Source: UniProtKB
  • integral component of plasma membrane Source: GO_Central
Complete GO annotation...

Keywords - Cellular componenti

Cell membrane, Membrane

Pathology & Biotechi

Disruption phenotypei

No visible phenotype under normal growth conditions, due to the redudancy with AHA1. Aha1 and aha2 double mutants are embryo lethal.1 Publication

Mutagenesis

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Mutagenesisi106 – 1061N → A, D, K, Q or T: Reduced proton transport. 1 Publication
Mutagenesisi655 – 6551R → A or D: No effect on ATP affinity, but reduced proton transport. 1 Publication
Mutagenesisi655 – 6551R → K: No effect on ATP affinity and proton transport. 1 Publication
Mutagenesisi684 – 6841D → A, V or R: No effect on ATP affinity, but loss of proton transport. 1 Publication
Mutagenesisi684 – 6841D → E: No effect on ATP affinity, but reduced proton transport. 1 Publication
Mutagenesisi684 – 6841D → N: Insensitive to the inhibitor vanadate and locked in the E1 conformation. No effect on ATP hydrolysis, but loss of proton transport. 2 Publications
Mutagenesisi881 – 8811T → A: Decreased phosphorylation by PSY1R. 1 Publication
Mutagenesisi881 – 8811T → D: No effect on 14-3-3 protein binding, but increased activity. 1 Publication
Mutagenesisi904 – 9041S → A: No effect on phosphorylation. 1 Publication
Mutagenesisi919 – 9191L → A: Loss of activation by lysophospholipids. 1 Publication
Mutagenesisi922 – 9221L → A: Increased activation by lysophospholipids. 1 Publication
Mutagenesisi924 – 9241T → A: No effect on phosphorylation. 1 Publication
Mutagenesisi931 – 9311S → A: Loss of phosphorylation and increased 14-3-3 protein binding. 1 Publication
Mutagenesisi931 – 9311S → D: Loss of interaction with 14-3-3 protein. 1 Publication
Mutagenesisi942 – 9421T → A: No effect on phosphorylation. 1 Publication
Mutagenesisi947 – 9471T → A: No effect on phosphorylation. 1 Publication

PTM / Processingi

Molecule processing

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Initiator methionineiRemovedCombined sources
Chaini2 – 948947ATPase 2, plasma membrane-typePRO_0000046275Add
BLAST

Amino acid modifications

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Modified residuei2 – 21N-acetylserineCombined sources
Modified residuei881 – 8811Phosphothreonine1 Publication
Modified residuei899 – 8991Phosphoserine1 Publication
Modified residuei931 – 9311Phosphoserine; by CIPK111 Publication
Modified residuei947 – 9471Phosphothreonine1 Publication

Post-translational modificationi

Phosphorylation at Thr-881 by PSY1R (PubMed:17651370, PubMed:25267325). This phosphrylation activates proton pumping (PubMed:25267325). Decreased phosphorylation in response to flg22 elicitation (PubMed:17651370).2 Publications
Phosphorylation at Ser-899 is specifically induced by RALF1, thus leading to the inhibition of proton transport (PubMed:24458638). Increased phosphorylation in response to flg22 elicitation (PubMed:17651370).2 Publications
Phosphorylation of Thr-947 induces the binding to 14-3-3 proteins, but phosphorylation of Ser-931 interfers with this binding no matter whether Thr-947 is phosphorylated or not (PubMed:10593986, PubMed:17483306). Decreased phosphorylation in response to flg22 elicitation (PubMed:17651370).3 Publications
Abscisic acid induces dephosphorylation of AHA2 in etiolated seedlings, suppressing ATP hydrolysis and hypocotyl elongation.1 Publication

Keywords - PTMi

Acetylation, Phosphoprotein

Proteomic databases

PaxDbiP19456.
PRIDEiP19456.

PTM databases

iPTMnetiP19456.

Expressioni

Tissue specificityi

Higher levels in roots than in shoots (PubMed:2143186). Expressed in epidermal and root cortex cells, in phloem, xylem and root hairs (PubMed:17483306). Detected in cotyledons, hypocotyls, roots and root hairs (PubMed:25267325).3 Publications

Developmental stagei

Expressed on the surface of developing seeds and up to the early globular stage of embryo development.1 Publication

Inductioni

Up-regulated by low nitrate conditions.1 Publication

Gene expression databases

ExpressionAtlasiP19456. baseline and differential.
GenevisibleiP19456. AT.

Interactioni

Subunit structurei

Binds to 14-3-3 proteins (PubMed:10593986). The binding is induced by phosphorylation of Thr-947 and it activates the H+-ATPase (PubMed:10593986). Interacts (via the R-domain) with PSY1R (via C-terminus) (PubMed:25267325). Part of a functional complex containing PSKR1, BAK1, CNGC17, and AHA (PubMed:26071421). Interacts with CNGC17 and PSKR1 (PubMed:26071421).3 Publications

Binary interactionsi

WithEntry#Exp.IntActNotes
CIPK11O229323EBI-2293350,EBI-537638

Protein-protein interaction databases

BioGridi14429. 39 interactions.
IntActiP19456. 4 interactions.
MINTiMINT-112688.
STRINGi3702.AT4G30190.2.

Structurei

Secondary structure

1
948
Legend: HelixTurnBeta strand
Show more details
Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Beta strandi15 – 184
Turni23 – 253
Beta strandi26 – 283
Helixi35 – 417
Beta strandi42 – 443
Turni50 – 534
Helixi67 – 693
Helixi72 – 787
Helixi79 – 824
Helixi96 – 1027
Turni103 – 12624
Turni145 – 1484
Beta strandi190 – 1923
Turni215 – 2195
Turni235 – 2406
Helixi241 – 25818
Turni260 – 2667
Helixi273 – 2808
Turni281 – 2844
Turni289 – 2913
Helixi292 – 2954
Turni296 – 2983
Helixi299 – 3046
Helixi314 – 3163
Helixi317 – 3204
Beta strandi327 – 3293
Helixi330 – 3345
Helixi355 – 36511
Beta strandi368 – 3703
Helixi374 – 3807
Turni402 – 4043
Beta strandi413 – 4164
Helixi426 – 4283
Beta strandi430 – 4334
Turni438 – 4425
Helixi443 – 4508
Turni451 – 4544
Beta strandi456 – 4605
Beta strandi467 – 4715
Beta strandi481 – 4855
Helixi491 – 50212
Beta strandi508 – 5136
Helixi515 – 5184
Helixi520 – 5234
Turni524 – 5263
Helixi540 – 5423
Turni543 – 5453
Helixi551 – 5566
Helixi566 – 57813
Helixi593 – 5986
Beta strandi599 – 6013
Beta strandi606 – 6083
Helixi609 – 6124
Helixi613 – 6153
Helixi625 – 6284
Helixi630 – 6334
Helixi635 – 65218
Turni653 – 6575
Helixi661 – 6644
Helixi673 – 68412
Turni704 – 7129
Helixi713 – 7175
Helixi721 – 7244
Beta strandi727 – 7293
Turni731 – 7388
Helixi747 – 7493
Helixi751 – 7544
Turni755 – 7573
Turni759 – 7613
Helixi766 – 7683
Beta strandi772 – 7743
Turni776 – 7783
Turni783 – 7875
Helixi789 – 7913
Turni794 – 7996
Beta strandi800 – 8045
Turni816 – 8194
Helixi820 – 8267
Helixi828 – 8303
Helixi832 – 84110

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
EntryMethodResolution (Å)ChainPositionsPDBsum
3B8CX-ray3.60A/B1-875[»]
ProteinModelPortaliP19456.
SMRiP19456. Positions 12-844, 900-942.
ModBaseiSearch...
MobiDBiSearch...

Miscellaneous databases

EvolutionaryTraceiP19456.

Family & Domainsi

Region

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Regioni946 – 9483Interaction with 14-3-3 proteins

Domaini

The C-terminus contains a R-domain composed of 2 autoinhibitory regions (863-885 and 904-919).1 Publication

Sequence similaritiesi

Keywords - Domaini

Transmembrane, Transmembrane helix

Phylogenomic databases

eggNOGiKOG0205. Eukaryota.
COG0474. LUCA.
HOGENOMiHOG000160005.
InParanoidiP19456.
KOiK01535.
PhylomeDBiP19456.

Family and domain databases

Gene3Di1.20.1110.10. 3 hits.
2.70.150.10. 2 hits.
3.40.1110.10. 1 hit.
InterProiIPR004014. ATPase_P-typ_cation-transptr_N.
IPR023299. ATPase_P-typ_cyto_domN.
IPR018303. ATPase_P-typ_P_site.
IPR023298. ATPase_P-typ_TM_dom.
IPR008250. ATPase_P-typ_transduc_dom_A.
IPR023214. HAD-like_dom.
IPR006534. P-type_ATPase_IIIA.
IPR001757. P_typ_ATPase.
[Graphical view]
PfamiPF00690. Cation_ATPase_N. 1 hit.
PF00122. E1-E2_ATPase. 1 hit.
[Graphical view]
PRINTSiPR00120. HATPASE.
SMARTiSM00831. Cation_ATPase_N. 1 hit.
[Graphical view]
SUPFAMiSSF56784. SSF56784. 2 hits.
TIGRFAMsiTIGR01647. ATPase-IIIA_H. 1 hit.
TIGR01494. ATPase_P-type. 2 hits.
PROSITEiPS00154. ATPASE_E1_E2. 1 hit.
[Graphical view]

Sequencei

Sequence statusi: Complete.

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

This entry describes 1 isoform i produced by alternative splicing. AlignAdd to basket

Note: A number of isoforms are produced. According to EST sequences.
Isoform 1 (identifier: P19456-1) [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
MSSLEDIKNE TVDLEKIPIE EVFQQLKCSR EGLTTQEGED RIQIFGPNKL
60 70 80 90 100
EEKKESKLLK FLGFMWNPLS WVMEMAAIMA IALANGDGRP PDWQDFVGII
110 120 130 140 150
CLLVINSTIS FIEENNAGNA AAALMAGLAP KTKVLRDGKW SEQEAAILVP
160 170 180 190 200
GDIVSIKLGD IIPADARLLE GDPLKVDQSA LTGESLPVTK HPGQEVFSGS
210 220 230 240 250
TCKQGEIEAV VIATGVHTFF GKAAHLVDST NQVGHFQKVL TAIGNFCICS
260 270 280 290 300
IAIGMVIEII VMYPIQRRKY RDGIDNLLVL LIGGIPIAMP TVLSVTMAIG
310 320 330 340 350
SHRLSQQGAI TKRMTAIEEM AGMDVLCSDK TGTLTLNKLS VDKNLVEVFC
360 370 380 390 400
KGVEKDQVLL FAAMASRVEN QDAIDAAMVG MLADPKEARA GIREVHFLPF
410 420 430 440 450
NPVDKRTALT YIDGSGNWHR VSKGAPEQIL ELAKASNDLS KKVLSIIDKY
460 470 480 490 500
AERGLRSLAV ARQVVPEKTK ESPGAPWEFV GLLPLFDPPR HDSAETIRRA
510 520 530 540 550
LNLGVNVKMI TGDQLAIGKE TGRRLGMGTN MYPSSALLGT HKDANLASIP
560 570 580 590 600
VEELIEKADG FAGVFPEHKY EIVKKLQERK HIVGMTGDGV NDAPALKKAD
610 620 630 640 650
IGIAVADATD AARGASDIVL TEPGLSVIIS AVLTSRAIFQ RMKNYTIYAV
660 670 680 690 700
SITIRIVFGF MLIALIWEFD FSAFMVLIIA ILNDGTIMTI SKDRVKPSPT
710 720 730 740 750
PDSWKLKEIF ATGVVLGGYQ AIMTVIFFWA AHKTDFFSDT FGVRSIRDNN
760 770 780 790 800
HELMGAVYLQ VSIISQALIF VTRSRSWSFV ERPGALLMIA FLIAQLIATL
810 820 830 840 850
IAVYANWEFA KIRGIGWGWA GVIWLYSIVT YFPLDVFKFA IRYILSGKAW
860 870 880 890 900
LNLFENKTAF TMKKDYGKEE REAQWALAQR TLHGLQPKEA VNIFPEKGSY
910 920 930 940
RELSEIAEQA KRRAEIARLR ELHTLKGHVE SVVKLKGLDI ETPSHYTV
Length:948
Mass (Da):104,401
Last modified:January 23, 2007 - v2
Checksum:i431F4021E99A3CEC
GO

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
J05570 Genomic DNA. Translation: AAA32751.1.
AL109796 Genomic DNA. Translation: CAB52463.1.
AL161576 Genomic DNA. Translation: CAB81012.1.
CP002687 Genomic DNA. Translation: AEE85731.1.
AY035075 mRNA. Translation: AAK59580.1.
BT000781 mRNA. Translation: AAN31920.1.
BT001969 mRNA. Translation: AAN71968.1.
PIRiA37116. PXMUP2.
RefSeqiNP_194748.1. NM_119165.3. [P19456-1]
UniGeneiAt.23014.

Genome annotation databases

EnsemblPlantsiAT4G30190.1; AT4G30190.1; AT4G30190. [P19456-1]
GeneIDi829142.
KEGGiath:AT4G30190.

Keywords - Coding sequence diversityi

Alternative splicing

Cross-referencesi

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
J05570 Genomic DNA. Translation: AAA32751.1.
AL109796 Genomic DNA. Translation: CAB52463.1.
AL161576 Genomic DNA. Translation: CAB81012.1.
CP002687 Genomic DNA. Translation: AEE85731.1.
AY035075 mRNA. Translation: AAK59580.1.
BT000781 mRNA. Translation: AAN31920.1.
BT001969 mRNA. Translation: AAN71968.1.
PIRiA37116. PXMUP2.
RefSeqiNP_194748.1. NM_119165.3. [P19456-1]
UniGeneiAt.23014.

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
EntryMethodResolution (Å)ChainPositionsPDBsum
3B8CX-ray3.60A/B1-875[»]
ProteinModelPortaliP19456.
SMRiP19456. Positions 12-844, 900-942.
ModBaseiSearch...
MobiDBiSearch...

Protein-protein interaction databases

BioGridi14429. 39 interactions.
IntActiP19456. 4 interactions.
MINTiMINT-112688.
STRINGi3702.AT4G30190.2.

Protein family/group databases

TCDBi3.A.3.3.9. the p-type atpase (p-atpase) superfamily.

PTM databases

iPTMnetiP19456.

Proteomic databases

PaxDbiP19456.
PRIDEiP19456.

Protocols and materials databases

Structural Biology KnowledgebaseSearch...

Genome annotation databases

EnsemblPlantsiAT4G30190.1; AT4G30190.1; AT4G30190. [P19456-1]
GeneIDi829142.
KEGGiath:AT4G30190.

Organism-specific databases

TAIRiAT4G30190.

Phylogenomic databases

eggNOGiKOG0205. Eukaryota.
COG0474. LUCA.
HOGENOMiHOG000160005.
InParanoidiP19456.
KOiK01535.
PhylomeDBiP19456.

Enzyme and pathway databases

BioCyciARA:AT4G30190-MONOMER.
ARA:GQT-365-MONOMER.
BRENDAi3.6.3.6. 399.
SABIO-RKP19456.

Miscellaneous databases

EvolutionaryTraceiP19456.
PROiP19456.

Gene expression databases

ExpressionAtlasiP19456. baseline and differential.
GenevisibleiP19456. AT.

Family and domain databases

Gene3Di1.20.1110.10. 3 hits.
2.70.150.10. 2 hits.
3.40.1110.10. 1 hit.
InterProiIPR004014. ATPase_P-typ_cation-transptr_N.
IPR023299. ATPase_P-typ_cyto_domN.
IPR018303. ATPase_P-typ_P_site.
IPR023298. ATPase_P-typ_TM_dom.
IPR008250. ATPase_P-typ_transduc_dom_A.
IPR023214. HAD-like_dom.
IPR006534. P-type_ATPase_IIIA.
IPR001757. P_typ_ATPase.
[Graphical view]
PfamiPF00690. Cation_ATPase_N. 1 hit.
PF00122. E1-E2_ATPase. 1 hit.
[Graphical view]
PRINTSiPR00120. HATPASE.
SMARTiSM00831. Cation_ATPase_N. 1 hit.
[Graphical view]
SUPFAMiSSF56784. SSF56784. 2 hits.
TIGRFAMsiTIGR01647. ATPase-IIIA_H. 1 hit.
TIGR01494. ATPase_P-type. 2 hits.
PROSITEiPS00154. ATPASE_E1_E2. 1 hit.
[Graphical view]
ProtoNetiSearch...

Entry informationi

Entry nameiPMA2_ARATH
AccessioniPrimary (citable) accession number: P19456
Entry historyi
Integrated into UniProtKB/Swiss-Prot: February 1, 1991
Last sequence update: January 23, 2007
Last modified: September 7, 2016
This is version 161 of the entry and version 2 of the sequence. [Complete history]
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programPlant Protein Annotation Program

Miscellaneousi

Miscellaneous

The catalytic mechanism involves at least four different enzyme conformational states named E1, E1P, E2P, and E2, with the E1P-E2P transition accompanying the transfer of ion across the membrane. E1P and E2P are phosphorylated intermediates.1 Publication

Keywords - Technical termi

3D-structure, Complete proteome, Reference proteome

Documents

  1. Arabidopsis thaliana
    Arabidopsis thaliana: entries and gene names
  2. PDB cross-references
    Index of Protein Data Bank (PDB) cross-references
  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.