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Protein

50S ribosomal protein L22

Gene

rplV

Organism
Escherichia coli (strain K12)
Status
Reviewed-Annotation score: Annotation score: 5 out of 5-Experimental evidence at protein leveli

Functioni

This protein binds specifically to 23S rRNA; its binding is stimulated by other ribosomal proteins, e.g. L4, L17, and L20. It is important during the early stages of 50S assembly. It makes multiple contacts with different domains of the 23S rRNA in the assembled 50S subunit and ribosome.
The globular domain of the protein is one of the proteins that surrounds the polypeptide exit tunnel on the outside of the subunit, while an extended beta-hairpin is found that penetrates into the center of the 70S ribosome where it lines the wall of the exit tunnel. Removal of most of this hairpin (residues 85-95) does not prevent its incorporation into 70S ribosomes. Two of the hairpin residues (91 and 93) seem to be involved in translation elongation arrest of the SecM protein, as their replacement by larger amino acids alleviates the arrest.

GO - Molecular functioni

  1. rRNA binding Source: UniProtKB-HAMAP
  2. structural constituent of ribosome Source: InterPro

GO - Biological processi

  1. response to antibiotic Source: UniProtKB-KW
  2. translation Source: UniProtKB-HAMAP
Complete GO annotation...

Keywords - Molecular functioni

Ribonucleoprotein, Ribosomal protein

Keywords - Biological processi

Antibiotic resistance

Keywords - Ligandi

RNA-binding, rRNA-binding

Enzyme and pathway databases

BioCyciEcoCyc:EG10882-MONOMER.
ECOL316407:JW3277-MONOMER.

Names & Taxonomyi

Protein namesi
Recommended name:
50S ribosomal protein L22
Gene namesi
Name:rplV
Synonyms:eryB
Ordered Locus Names:b3315, JW3277
OrganismiEscherichia coli (strain K12)
Taxonomic identifieri83333 [NCBI]
Taxonomic lineageiBacteriaProteobacteriaGammaproteobacteriaEnterobacterialesEnterobacteriaceaeEscherichia
ProteomesiUP000000318: Chromosome, UP000000625: Chromosome

Organism-specific databases

EcoGeneiEG10882. rplV.

Subcellular locationi

GO - Cellular componenti

  1. cytosolic large ribosomal subunit Source: EcoCyc
Complete GO annotation...

Pathology & Biotechi

Mutagenesis

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Mutagenesisi82 – 9918Missing : Incorporated into ribosomes in vivo, but is easily removed by a salt wash. 1 PublicationAdd
BLAST
Mutagenesisi85 – 9511Missing : Incorporates into ribosomes in vivo. 1 PublicationAdd
BLAST
Mutagenesisi91 – 911G → A, D or S: Abolishes translation elongation arrest of SecM. 1 Publication
Mutagenesisi93 – 931A → S, T or V: Abolishes translation elongation arrest of SecM. 1 Publication

PTM / Processingi

Molecule processing

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Chaini1 – 11011050S ribosomal protein L22PRO_0000125153Add
BLAST

Proteomic databases

PaxDbiP61175.
PRIDEiP61175.

Expressioni

Gene expression databases

GenevestigatoriP61175.

Interactioni

Subunit structurei

Part of the 50S ribosomal subunit.

Binary interactionsi

WithEntry#Exp.IntActNotes
ubiGP179932EBI-542255,EBI-559367

Protein-protein interaction databases

DIPiDIP-35983N.
IntActiP61175. 128 interactions.
MINTiMINT-1253134.
STRINGi511145.b3315.

Structurei

Secondary structure

1
110
Legend: HelixTurnBeta strand
Show more details
Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Beta strandi3 – 1210Combined sources
Helixi14 – 2411Combined sources
Beta strandi25 – 273Combined sources
Helixi29 – 379Combined sources
Helixi42 – 6019Combined sources
Beta strandi62 – 643Combined sources
Helixi66 – 683Combined sources
Beta strandi70 – 789Combined sources
Beta strandi82 – 876Combined sources
Helixi89 – 913Combined sources
Beta strandi93 – 986Combined sources
Beta strandi101 – 1088Combined sources

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
EntryMethodResolution (Å)ChainPositionsPDBsum
2J28electron microscopy8.00S1-110[»]
2RDOelectron microscopy9.10S1-110[»]
3BBXelectron microscopy10.00S1-110[»]
3J5Lelectron microscopy6.60S1-110[»]
3J7Zelectron microscopy3.90S1-110[»]
4CSUelectron microscopy5.50S1-110[»]
4U1UX-ray2.95S1-110[»]
4U1VX-ray3.00S1-110[»]
4U20X-ray2.90S1-110[»]
4U24X-ray2.90S1-110[»]
4U25X-ray2.90S1-110[»]
4U26X-ray2.80S1-110[»]
4U27X-ray2.80S1-110[»]
4V47electron microscopy12.30Q1-110[»]
4V48electron microscopy11.50Q1-110[»]
4V4HX-ray3.46S1-110[»]
4V4QX-ray3.46S1-110[»]
4V4Velectron microscopy15.00Q5-110[»]
4V4Welectron microscopy15.00Q5-110[»]
4V50X-ray3.22S1-110[»]
4V52X-ray3.21S1-110[»]
4V53X-ray3.54S1-110[»]
4V54X-ray3.30S1-110[»]
4V55X-ray4.00S1-110[»]
4V56X-ray3.93S1-110[»]
4V57X-ray3.50S1-110[»]
4V5BX-ray3.74S1-110[»]
4V5Helectron microscopy5.80S1-110[»]
4V5YX-ray4.45S1-110[»]
4V64X-ray3.50S1-110[»]
4V65electron microscopy-L1-110[»]
4V66electron microscopy-L1-110[»]
4V69electron microscopy6.70S1-110[»]
4V6CX-ray3.19S1-110[»]
4V6DX-ray3.81S1-110[»]
4V6EX-ray3.71S1-110[»]
4V6Kelectron microscopy-T1-110[»]
4V6Lelectron microscopy-T1-110[»]
4V6Melectron microscopy-S1-110[»]
4V6Nelectron microscopy12.10U1-110[»]
4V6Oelectron microscopy14.70U1-110[»]
4V6Pelectron microscopy13.50U1-110[»]
4V6Qelectron microscopy11.50U1-110[»]
4V6Relectron microscopy11.50U1-110[»]
4V6Selectron microscopy13.10U1-110[»]
4V6Telectron microscopy8.30S1-110[»]
4V6Velectron microscopy9.80W1-110[»]
4V6Yelectron microscopy12.00S1-110[»]
4V6Zelectron microscopy12.00S1-110[»]
4V70electron microscopy17.00S1-110[»]
4V71electron microscopy20.00S1-110[»]
4V72electron microscopy13.00S1-110[»]
4V73electron microscopy15.00S1-110[»]
4V74electron microscopy17.00S1-110[»]
4V75electron microscopy12.00S1-110[»]
4V76electron microscopy17.00S1-110[»]
4V77electron microscopy17.00S1-110[»]
4V78electron microscopy20.00S1-110[»]
4V79electron microscopy15.00S1-110[»]
4V7Aelectron microscopy9.00S1-110[»]
4V7Belectron microscopy6.80S1-110[»]
4V7Celectron microscopy7.60U1-110[»]
4V7Delectron microscopy7.60V1-110[»]
4V7Ielectron microscopy-S1-110[»]
4V7SX-ray3.25S1-110[»]
4V7TX-ray3.19S1-110[»]
4V7UX-ray3.10S1-110[»]
4V7VX-ray3.29S1-110[»]
4V85X-ray3.20W1-110[»]
4V89X-ray3.70W1-110[»]
4V9CX-ray3.30S1-110[»]
4V9DX-ray3.00S1-110[»]
4V9OX-ray2.90S1-110[»]
4V9PX-ray2.90S1-110[»]
4WF1X-ray3.09S1-110[»]
4WWWX-ray3.30S1-110[»]
ProteinModelPortaliP61175.
SMRiP61175. Positions 1-110.
ModBaseiSearch...
MobiDBiSearch...

Miscellaneous databases

EvolutionaryTraceiP61175.

Family & Domainsi

Sequence similaritiesi

Belongs to the ribosomal protein L22P family.Curated

Phylogenomic databases

eggNOGiCOG0091.
HOGENOMiHOG000205046.
InParanoidiP61175.
KOiK02890.
OMAiGRAFRIN.
OrthoDBiEOG6V4GKB.
PhylomeDBiP61175.

Family and domain databases

Gene3Di3.90.470.10. 1 hit.
HAMAPiMF_01331_B. Ribosomal_L22_B.
InterProiIPR001063. Ribosomal_L22.
IPR018260. Ribosomal_L22/L17_CS.
IPR005727. Ribosomal_L22_bac/chlpt-type.
[Graphical view]
PANTHERiPTHR13501. PTHR13501. 1 hit.
PfamiPF00237. Ribosomal_L22. 1 hit.
[Graphical view]
SUPFAMiSSF54843. SSF54843. 1 hit.
TIGRFAMsiTIGR01044. rplV_bact. 1 hit.
PROSITEiPS00464. RIBOSOMAL_L22. 1 hit.
[Graphical view]

Sequencei

Sequence statusi: Complete.

P61175-1 [UniParc]FASTAAdd to basket

« Hide

        10         20         30         40         50
METIAKHRHA RSSAQKVRLV ADLIRGKKVS QALDILTYTN KKAAVLVKKV
60 70 80 90 100
LESAIANAEH NDGADIDDLK VTKIFVDEGP SMKRIMPRAK GRADRILKRT
110
SHITVVVSDR
Length:110
Mass (Da):12,226
Last modified:July 21, 1986 - v1
Checksum:iF0E0C6982772277C
GO

Mass spectrometryi

Molecular mass is 12225.3 Da from positions 1 - 110. Determined by MALDI. 1 Publication

Natural variant

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Natural varianti8 – 81R → C in strain: SK1048; decreases translational rate, tRNA binding and subunit association at 44 degrees Celsius; does not alter 23S rRNA or L4 interactions; not erythromycin resistant.
Natural varianti82 – 843Missing in strain: N281; confers erythromycin resistance; ribosomes bind erythromycin normally and have normal peptidyltransferase activity; 50S subunits assemble normally, even in the presence of drug; the protein is incorporated into ribosomes in vivo; abolishes translation elongation arrest of SecM.

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
X02613 Genomic DNA. Translation: CAA26465.1.
U18997 Genomic DNA. Translation: AAA58112.1.
U00096 Genomic DNA. Translation: AAC76340.1.
AP009048 Genomic DNA. Translation: BAE77976.1.
PIRiG23129. R5EC22.
RefSeqiNP_417774.1. NC_000913.3.
YP_492117.1. NC_007779.1.

Genome annotation databases

EnsemblBacteriaiAAC76340; AAC76340; b3315.
BAE77976; BAE77976; BAE77976.
GeneIDi12932293.
947813.
KEGGiecj:Y75_p3861.
eco:b3315.
PATRICi32122062. VBIEscCol129921_3408.

Cross-referencesi

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
X02613 Genomic DNA. Translation: CAA26465.1.
U18997 Genomic DNA. Translation: AAA58112.1.
U00096 Genomic DNA. Translation: AAC76340.1.
AP009048 Genomic DNA. Translation: BAE77976.1.
PIRiG23129. R5EC22.
RefSeqiNP_417774.1. NC_000913.3.
YP_492117.1. NC_007779.1.

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
EntryMethodResolution (Å)ChainPositionsPDBsum
2J28electron microscopy8.00S1-110[»]
2RDOelectron microscopy9.10S1-110[»]
3BBXelectron microscopy10.00S1-110[»]
3J5Lelectron microscopy6.60S1-110[»]
3J7Zelectron microscopy3.90S1-110[»]
4CSUelectron microscopy5.50S1-110[»]
4U1UX-ray2.95S1-110[»]
4U1VX-ray3.00S1-110[»]
4U20X-ray2.90S1-110[»]
4U24X-ray2.90S1-110[»]
4U25X-ray2.90S1-110[»]
4U26X-ray2.80S1-110[»]
4U27X-ray2.80S1-110[»]
4V47electron microscopy12.30Q1-110[»]
4V48electron microscopy11.50Q1-110[»]
4V4HX-ray3.46S1-110[»]
4V4QX-ray3.46S1-110[»]
4V4Velectron microscopy15.00Q5-110[»]
4V4Welectron microscopy15.00Q5-110[»]
4V50X-ray3.22S1-110[»]
4V52X-ray3.21S1-110[»]
4V53X-ray3.54S1-110[»]
4V54X-ray3.30S1-110[»]
4V55X-ray4.00S1-110[»]
4V56X-ray3.93S1-110[»]
4V57X-ray3.50S1-110[»]
4V5BX-ray3.74S1-110[»]
4V5Helectron microscopy5.80S1-110[»]
4V5YX-ray4.45S1-110[»]
4V64X-ray3.50S1-110[»]
4V65electron microscopy-L1-110[»]
4V66electron microscopy-L1-110[»]
4V69electron microscopy6.70S1-110[»]
4V6CX-ray3.19S1-110[»]
4V6DX-ray3.81S1-110[»]
4V6EX-ray3.71S1-110[»]
4V6Kelectron microscopy-T1-110[»]
4V6Lelectron microscopy-T1-110[»]
4V6Melectron microscopy-S1-110[»]
4V6Nelectron microscopy12.10U1-110[»]
4V6Oelectron microscopy14.70U1-110[»]
4V6Pelectron microscopy13.50U1-110[»]
4V6Qelectron microscopy11.50U1-110[»]
4V6Relectron microscopy11.50U1-110[»]
4V6Selectron microscopy13.10U1-110[»]
4V6Telectron microscopy8.30S1-110[»]
4V6Velectron microscopy9.80W1-110[»]
4V6Yelectron microscopy12.00S1-110[»]
4V6Zelectron microscopy12.00S1-110[»]
4V70electron microscopy17.00S1-110[»]
4V71electron microscopy20.00S1-110[»]
4V72electron microscopy13.00S1-110[»]
4V73electron microscopy15.00S1-110[»]
4V74electron microscopy17.00S1-110[»]
4V75electron microscopy12.00S1-110[»]
4V76electron microscopy17.00S1-110[»]
4V77electron microscopy17.00S1-110[»]
4V78electron microscopy20.00S1-110[»]
4V79electron microscopy15.00S1-110[»]
4V7Aelectron microscopy9.00S1-110[»]
4V7Belectron microscopy6.80S1-110[»]
4V7Celectron microscopy7.60U1-110[»]
4V7Delectron microscopy7.60V1-110[»]
4V7Ielectron microscopy-S1-110[»]
4V7SX-ray3.25S1-110[»]
4V7TX-ray3.19S1-110[»]
4V7UX-ray3.10S1-110[»]
4V7VX-ray3.29S1-110[»]
4V85X-ray3.20W1-110[»]
4V89X-ray3.70W1-110[»]
4V9CX-ray3.30S1-110[»]
4V9DX-ray3.00S1-110[»]
4V9OX-ray2.90S1-110[»]
4V9PX-ray2.90S1-110[»]
4WF1X-ray3.09S1-110[»]
4WWWX-ray3.30S1-110[»]
ProteinModelPortaliP61175.
SMRiP61175. Positions 1-110.
ModBaseiSearch...
MobiDBiSearch...

Protein-protein interaction databases

DIPiDIP-35983N.
IntActiP61175. 128 interactions.
MINTiMINT-1253134.
STRINGi511145.b3315.

Chemistry

ChEMBLiCHEMBL2363135.

Proteomic databases

PaxDbiP61175.
PRIDEiP61175.

Protocols and materials databases

Structural Biology KnowledgebaseSearch...

Genome annotation databases

EnsemblBacteriaiAAC76340; AAC76340; b3315.
BAE77976; BAE77976; BAE77976.
GeneIDi12932293.
947813.
KEGGiecj:Y75_p3861.
eco:b3315.
PATRICi32122062. VBIEscCol129921_3408.

Organism-specific databases

EchoBASEiEB0875.
EcoGeneiEG10882. rplV.

Phylogenomic databases

eggNOGiCOG0091.
HOGENOMiHOG000205046.
InParanoidiP61175.
KOiK02890.
OMAiGRAFRIN.
OrthoDBiEOG6V4GKB.
PhylomeDBiP61175.

Enzyme and pathway databases

BioCyciEcoCyc:EG10882-MONOMER.
ECOL316407:JW3277-MONOMER.

Miscellaneous databases

EvolutionaryTraceiP61175.
PROiP61175.

Gene expression databases

GenevestigatoriP61175.

Family and domain databases

Gene3Di3.90.470.10. 1 hit.
HAMAPiMF_01331_B. Ribosomal_L22_B.
InterProiIPR001063. Ribosomal_L22.
IPR018260. Ribosomal_L22/L17_CS.
IPR005727. Ribosomal_L22_bac/chlpt-type.
[Graphical view]
PANTHERiPTHR13501. PTHR13501. 1 hit.
PfamiPF00237. Ribosomal_L22. 1 hit.
[Graphical view]
SUPFAMiSSF54843. SSF54843. 1 hit.
TIGRFAMsiTIGR01044. rplV_bact. 1 hit.
PROSITEiPS00464. RIBOSOMAL_L22. 1 hit.
[Graphical view]
ProtoNetiSearch...

Publicationsi

« Hide 'large scale' publications
  1. "Amino acid sequence of protein L22 from the large subunit of the Escherichia coli ribosome."
    Wittmann-Liebold B., Greuer B.
    FEBS Lett. 121:105-112(1980) [PubMed] [Europe PMC] [Abstract]
    Cited for: PROTEIN SEQUENCE.
  2. "Structure of the Escherichia coli S10 ribosomal protein operon."
    Zurawski G., Zurawski S.M.
    Nucleic Acids Res. 13:4521-4526(1985) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA].
  3. Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
    Strain: K12 / MG1655 / ATCC 47076.
  4. "Highly accurate genome sequences of Escherichia coli K-12 strains MG1655 and W3110."
    Hayashi K., Morooka N., Yamamoto Y., Fujita K., Isono K., Choi S., Ohtsubo E., Baba T., Wanner B.L., Mori H., Horiuchi T.
    Mol. Syst. Biol. 2:E1-E5(2006) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
    Strain: K12 / W3110 / ATCC 27325 / DSM 5911.
  5. "Biochemical and genetic studies on two different types of erythromycin resistant mutants of Escherichia coli with altered ribosomal proteins."
    Wittmann H.G., Stoffler G., Apirion D., Rosen L., Tanaka K., Tamaki M., Takata R., Dekio S., Otaka E.
    Mol. Gen. Genet. 127:175-189(1973) [PubMed] [Europe PMC] [Abstract]
    Cited for: BIOCHEMICAL CHARACTERIZATION OF ERYTHROMYCIN-RESISTANT VARIANT N281.
    Strain: N281.
  6. "A temperature-sensitive mutant of Escherichia coli with an alteration in ribosomal protein L22."
    Burnette-Vick B., Champney W.S., Musich P.R.
    Genetica 94:17-25(1994) [PubMed] [Europe PMC] [Abstract]
    Cited for: TEMPERATURE-SENSITIVE VARIANT.
    Strain: SK1048.
  7. "Ribosomal protein gene sequence changes in erythromycin-resistant mutants of Escherichia coli."
    Chittum H.S., Champney W.S.
    J. Bacteriol. 176:6192-6198(1994) [PubMed] [Europe PMC] [Abstract]
    Cited for: IDENTIFICATION OF CHANGES IN ERYTHROMYCIN-RESISTANT VARIANT N281.
    Strain: N281.
  8. "Erythromycin inhibits the assembly of the large ribosomal subunit in growing Escherichia coli cells."
    Chittum H.S., Champney W.S.
    Curr. Microbiol. 30:273-279(1995) [PubMed] [Europe PMC] [Abstract]
    Cited for: ERYTHROMYCIN AND RIBOSOME ASSEMBLY.
    Strain: N281 and SK901.
  9. "The ribosomal exit tunnel functions as a discriminating gate."
    Nakatogawa H., Ito K.
    Cell 108:629-636(2002) [PubMed] [Europe PMC] [Abstract]
    Cited for: MUTAGENESIS OF GLY-91 AND ALA-93.
  10. "The extended loops of ribosomal proteins L4 and L22 are not required for ribosome assembly or L4-mediated autogenous control."
    Zengel J.M., Jerauld A., Walker A., Wahl M.C., Lindahl L.
    RNA 9:1188-1197(2003) [PubMed] [Europe PMC] [Abstract]
    Cited for: MUTAGENESIS TO EXAMINE REQUIREMENTS FOR RIBOSOME ASSEMBLY.
    Strain: K12 / LL308.
  11. "Observation of Escherichia coli ribosomal proteins and their posttranslational modifications by mass spectrometry."
    Arnold R.J., Reilly J.P.
    Anal. Biochem. 269:105-112(1999) [PubMed] [Europe PMC] [Abstract]
    Cited for: MASS SPECTROMETRY.
    Strain: K12 / ATCC 25404 / DSM 5698 / NCIMB 11290.
  12. "Study of the structural dynamics of the E. coli 70S ribosome using real-space refinement."
    Gao H., Sengupta J., Valle M., Korostelev A., Eswar N., Stagg S.M., Van Roey P., Agrawal R.K., Harvey S.C., Sali A., Chapman M.S., Frank J.
    Cell 113:789-801(2003) [PubMed] [Europe PMC] [Abstract]
    Cited for: STRUCTURE BY ELECTRON MICROSCOPY (11.50 ANGSTROMS).
    Strain: MRE-600.
  13. "The polypeptide tunnel system in the ribosome and its gating in erythromycin resistance mutants of L4 and L22."
    Gabashvili I.S., Gregory S.T., Valle M., Grassucci R., Worbs M., Wahl M.C., Dahlberg A.E., Frank J.
    Mol. Cell 8:181-188(2001) [PubMed] [Europe PMC] [Abstract]
    Cited for: STRUCTURE BY ELECTRON MICROSCOPY (17.1 ANGSTROMS), EFFECT OF THE ERYTHROMYCIN-RESISTANT VARIANT ON THE POLYPEPTIDE EXIT TUNNEL.
    Strain: N281.
  14. Cited for: X-RAY CRYSTALLOGRAPHY (3.46 ANGSTROMS) OF 2 DIFFERENT RIBOSOME STRUCTURES.
    Strain: MRE-600.

Entry informationi

Entry nameiRL22_ECOLI
AccessioniPrimary (citable) accession number: P61175
Secondary accession number(s): P02423, Q2M6Y0
Entry historyi
Integrated into UniProtKB/Swiss-Prot: July 21, 1986
Last sequence update: July 21, 1986
Last modified: March 4, 2015
This is version 119 of the entry and version 1 of the sequence. [Complete history]
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programProkaryotic Protein Annotation Program

Miscellaneousi

Miscellaneous

The wild-type allele (erythromycin sensitive) is dominant over the resistant allele, and is also dominant over the temperature-sensitive allele at both low and high temperatures.

Keywords - Technical termi

3D-structure, Complete proteome, Direct protein sequencing, Reference proteome

Documents

  1. Escherichia coli
    Escherichia coli (strain K12): entries and cross-references to EcoGene
  2. PDB cross-references
    Index of Protein Data Bank (PDB) cross-references
  3. Ribosomal proteins
    Ribosomal proteins families and list of entries
  4. SIMILARITY comments
    Index of protein domains and families

External Data

Dasty 3

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 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.