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Protein

Eukaryotic translation initiation factor 5

Gene

EIF5

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

Functioni

Catalyzes the hydrolysis of GTP bound to the 40S ribosomal initiation complex (40S.mRNA.Met-tRNA[F].eIF-2.GTP) with the subsequent joining of a 60S ribosomal subunit resulting in the release of eIF-2 and the guanine nucleotide. The subsequent joining of a 60S ribosomal subunit results in the formation of a functional 80S initiation complex (80S.mRNA.Met-tRNA[F]).

Regions

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Nucleotide bindingi27 – 348GTPSequence Analysis

GO - Molecular functioni

  1. GTPase activity Source: ProtInc
  2. GTP binding Source: UniProtKB-KW
  3. poly(A) RNA binding Source: UniProtKB
  4. translation factor activity, nucleic acid binding Source: ProtInc
  5. translation initiation factor activity Source: UniProtKB

GO - Biological processi

  1. cellular protein metabolic process Source: Reactome
  2. gene expression Source: Reactome
  3. GTP catabolic process Source: GOC
  4. regulation of translational initiation Source: ProtInc
  5. translation Source: Reactome
  6. translational initiation Source: UniProtKB
Complete GO annotation...

Keywords - Molecular functioni

Initiation factor

Keywords - Biological processi

Protein biosynthesis

Keywords - Ligandi

GTP-binding, Nucleotide-binding

Enzyme and pathway databases

ReactomeiREACT_2085. GTP hydrolysis and joining of the 60S ribosomal subunit.
REACT_931. Ribosomal scanning and start codon recognition.

Names & Taxonomyi

Protein namesi
Recommended name:
Eukaryotic translation initiation factor 5
Short name:
eIF-5
Gene namesi
Name:EIF5
OrganismiHomo sapiens (Human)
Taxonomic identifieri9606 [NCBI]
Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaEuarchontogliresPrimatesHaplorrhiniCatarrhiniHominidaeHomo
ProteomesiUP000005640: Chromosome 14

Organism-specific databases

HGNCiHGNC:3299. EIF5.

Subcellular locationi

GO - Cellular componenti

  1. cytoplasm Source: HPA
  2. cytosol Source: UniProtKB
  3. plasma membrane Source: HPA
Complete GO annotation...

Pathology & Biotechi

Organism-specific databases

PharmGKBiPA27725.

PTM / Processingi

Molecule processing

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Chaini1 – 431431Eukaryotic translation initiation factor 5PRO_0000212516Add
BLAST

Amino acid modifications

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Modified residuei10 – 101Phosphoserine2 Publications
Modified residuei229 – 2291Phosphoserine1 Publication
Modified residuei389 – 3891Phosphoserine4 Publications
Modified residuei390 – 3901Phosphoserine4 Publications
Modified residuei419 – 4191Phosphoserine2 Publications

Keywords - PTMi

Phosphoprotein

Proteomic databases

MaxQBiP55010.
PaxDbiP55010.
PeptideAtlasiP55010.
PRIDEiP55010.

PTM databases

PhosphoSiteiP55010.

Expressioni

Gene expression databases

BgeeiP55010.
CleanExiHS_EIF5.
ExpressionAtlasiP55010. baseline and differential.
GenevestigatoriP55010.

Organism-specific databases

HPAiCAB004226.
HPA000867.

Interactioni

Protein-protein interaction databases

BioGridi108298. 42 interactions.
IntActiP55010. 6 interactions.
MINTiMINT-5004352.
STRINGi9606.ENSP00000216554.

Structurei

Secondary structure

1
431
Legend: HelixTurnBeta strand
Show more details
Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Beta strandi2 – 65Combined sources
Beta strandi17 – 193Combined sources
Beta strandi23 – 253Combined sources
Beta strandi27 – 315Combined sources
Beta strandi33 – 364Combined sources
Helixi39 – 457Combined sources
Helixi51 – 6111Combined sources
Beta strandi65 – 684Combined sources
Turni69 – 724Combined sources
Beta strandi73 – 786Combined sources
Helixi82 – 9514Combined sources
Turni100 – 1023Combined sources
Beta strandi103 – 1053Combined sources
Beta strandi108 – 1125Combined sources
Turni113 – 1164Combined sources
Beta strandi117 – 1215Combined sources
Beta strandi123 – 1253Combined sources
Beta strandi128 – 1303Combined sources
Beta strandi133 – 1364Combined sources
Helixi137 – 1437Combined sources
Helixi236 – 25217Combined sources
Helixi256 – 2583Combined sources
Helixi260 – 26910Combined sources
Helixi273 – 2753Combined sources
Helixi276 – 2849Combined sources
Helixi289 – 2957Combined sources
Helixi297 – 3048Combined sources
Helixi308 – 32417Combined sources
Helixi326 – 3294Combined sources
Helixi330 – 3323Combined sources
Helixi333 – 34210Combined sources
Helixi348 – 3569Combined sources
Beta strandi361 – 3633Combined sources
Helixi365 – 38319Combined sources
Helixi400 – 4089Combined sources

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
EntryMethodResolution (Å)ChainPositionsPDBsum
2E9HNMR-A1-150[»]
2G2KNMR-A2-170[»]
2IU1X-ray1.80A232-431[»]
ProteinModelPortaliP55010.
SMRiP55010. Positions 3-150, 232-407.
ModBaseiSearch...
MobiDBiSearch...

Miscellaneous databases

EvolutionaryTraceiP55010.

Family & Domainsi

Domains and Repeats

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Domaini233 – 392160W2PROSITE-ProRule annotationAdd
BLAST

Compositional bias

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Compositional biasi196 – 2027Asp/Glu-rich (highly acidic)
Compositional biasi384 – 40219Asp/Glu-rich (highly acidic)Add
BLAST
Compositional biasi423 – 4297Asp-rich (acidic)

Sequence similaritiesi

Belongs to the eIF-2-beta/eIF-5 family.Curated
Contains 1 W2 domain.PROSITE-ProRule annotation

Phylogenomic databases

eggNOGiCOG1601.
GeneTreeiENSGT00390000016478.
HOGENOMiHOG000214327.
HOVERGENiHBG006132.
InParanoidiP55010.
KOiK03262.
OMAiMHQAQLL.
OrthoDBiEOG7FV3QF.
PhylomeDBiP55010.
TreeFamiTF101533.

Family and domain databases

Gene3Di1.25.40.180. 1 hit.
3.30.30.50. 1 hit.
InterProiIPR016024. ARM-type_fold.
IPR016021. MIF4-like_typ_1/2/3.
IPR002735. Transl_init_fac_IF2/IF5.
IPR016189. Transl_init_fac_IF2/IF5_N.
IPR016190. Transl_init_fac_IF2/IF5_Zn-bd.
IPR003307. W2_domain.
[Graphical view]
PfamiPF01873. eIF-5_eIF-2B. 1 hit.
PF02020. W2. 1 hit.
[Graphical view]
SMARTiSM00653. eIF2B_5. 1 hit.
SM00515. eIF5C. 1 hit.
[Graphical view]
SUPFAMiSSF100966. SSF100966. 1 hit.
SSF48371. SSF48371. 1 hit.
SSF75689. SSF75689. 1 hit.
PROSITEiPS51363. W2. 1 hit.
[Graphical view]

Sequencei

Sequence statusi: Complete.

P55010-1 [UniParc]FASTAAdd to Basket

« Hide

        10         20         30         40         50
MSVNVNRSVS DQFYRYKMPR LIAKVEGKGN GIKTVIVNMV DVAKALNRPP
60 70 80 90 100
TYPTKYFGCE LGAQTQFDVK NDRYIVNGSH EANKLQDMLD GFIKKFVLCP
110 120 130 140 150
ECENPETDLH VNPKKQTIGN SCKACGYRGM LDTHHKLCTF ILKNPPENSD
160 170 180 190 200
SGTGKKEKEK KNRKGKDKEN GSVSSSETPP PPPPPNEINP PPHTMEEEED
210 220 230 240 250
DDWGEDTTEE AQRRRMDEIS DHAKVLTLSD DLERTIEERV NILFDFVKKK
260 270 280 290 300
KEEGVIDSSD KEIVAEAERL DVKAMGPLVL TEVLFNEKIR EQIKKYRRHF
310 320 330 340 350
LRFCHNNKKA QRYLLHGLEC VVAMHQAQLI SKIPHILKEM YDADLLEEEV
360 370 380 390 400
IISWSEKASK KYVSKELAKE IRVKAEPFIK WLKEAEEESS GGEEEDEDEN
410 420 430
IEVVYSKAAS VPKVETVKSD NKDDDIDIDA I
Length:431
Mass (Da):49,223
Last modified:January 10, 2003 - v2
Checksum:iC6CCC3A255F9B9BC
GO

Experimental Info

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Sequence conflicti60 – 601E → G in CAB45711. (PubMed:11230166)Curated
Sequence conflicti203 – 2031W → S in AAC50572. (PubMed:8663286)Curated
Sequence conflicti295 – 2951K → E in CAB45711. (PubMed:11230166)Curated
Sequence conflicti311 – 3111Q → K in AAH32866. (PubMed:15489334)Curated

Natural variant

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Natural varianti418 – 4181K → M in a breast cancer sample; somatic mutation. 1 Publication
VAR_036467

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
U49436 mRNA. Translation: AAC50572.1.
AL080102 mRNA. Translation: CAB45711.1.
AK026933 mRNA. Translation: BAB15593.1.
BX537367 mRNA. Translation: CAD97610.1.
CH471061 Genomic DNA. Translation: EAW81809.1.
BC007728 mRNA. Translation: AAH07728.1.
BC032866 mRNA. Translation: AAH32866.1.
CCDSiCCDS9980.1.
PIRiT12450.
RefSeqiNP_001960.2. NM_001969.4.
NP_892116.2. NM_183004.4.
UniGeneiHs.433702.
Hs.741278.

Genome annotation databases

EnsembliENST00000216554; ENSP00000216554; ENSG00000100664.
ENST00000392715; ENSP00000376477; ENSG00000100664.
ENST00000558506; ENSP00000453743; ENSG00000100664.
GeneIDi1983.
KEGGihsa:1983.
UCSCiuc001ymq.4. human.

Polymorphism databases

DMDMi27735202.

Keywords - Coding sequence diversityi

Polymorphism

Cross-referencesi

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
U49436 mRNA. Translation: AAC50572.1.
AL080102 mRNA. Translation: CAB45711.1.
AK026933 mRNA. Translation: BAB15593.1.
BX537367 mRNA. Translation: CAD97610.1.
CH471061 Genomic DNA. Translation: EAW81809.1.
BC007728 mRNA. Translation: AAH07728.1.
BC032866 mRNA. Translation: AAH32866.1.
CCDSiCCDS9980.1.
PIRiT12450.
RefSeqiNP_001960.2. NM_001969.4.
NP_892116.2. NM_183004.4.
UniGeneiHs.433702.
Hs.741278.

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
EntryMethodResolution (Å)ChainPositionsPDBsum
2E9HNMR-A1-150[»]
2G2KNMR-A2-170[»]
2IU1X-ray1.80A232-431[»]
ProteinModelPortaliP55010.
SMRiP55010. Positions 3-150, 232-407.
ModBaseiSearch...
MobiDBiSearch...

Protein-protein interaction databases

BioGridi108298. 42 interactions.
IntActiP55010. 6 interactions.
MINTiMINT-5004352.
STRINGi9606.ENSP00000216554.

PTM databases

PhosphoSiteiP55010.

Polymorphism databases

DMDMi27735202.

Proteomic databases

MaxQBiP55010.
PaxDbiP55010.
PeptideAtlasiP55010.
PRIDEiP55010.

Protocols and materials databases

DNASUi1983.
Structural Biology KnowledgebaseSearch...

Genome annotation databases

EnsembliENST00000216554; ENSP00000216554; ENSG00000100664.
ENST00000392715; ENSP00000376477; ENSG00000100664.
ENST00000558506; ENSP00000453743; ENSG00000100664.
GeneIDi1983.
KEGGihsa:1983.
UCSCiuc001ymq.4. human.

Organism-specific databases

CTDi1983.
GeneCardsiGC14P103800.
HGNCiHGNC:3299. EIF5.
HPAiCAB004226.
HPA000867.
MIMi601710. gene.
neXtProtiNX_P55010.
PharmGKBiPA27725.
GenAtlasiSearch...

Phylogenomic databases

eggNOGiCOG1601.
GeneTreeiENSGT00390000016478.
HOGENOMiHOG000214327.
HOVERGENiHBG006132.
InParanoidiP55010.
KOiK03262.
OMAiMHQAQLL.
OrthoDBiEOG7FV3QF.
PhylomeDBiP55010.
TreeFamiTF101533.

Enzyme and pathway databases

ReactomeiREACT_2085. GTP hydrolysis and joining of the 60S ribosomal subunit.
REACT_931. Ribosomal scanning and start codon recognition.

Miscellaneous databases

ChiTaRSiEIF5. human.
EvolutionaryTraceiP55010.
GeneWikiiEIF5.
GenomeRNAii1983.
NextBioi8031.
PROiP55010.
SOURCEiSearch...

Gene expression databases

BgeeiP55010.
CleanExiHS_EIF5.
ExpressionAtlasiP55010. baseline and differential.
GenevestigatoriP55010.

Family and domain databases

Gene3Di1.25.40.180. 1 hit.
3.30.30.50. 1 hit.
InterProiIPR016024. ARM-type_fold.
IPR016021. MIF4-like_typ_1/2/3.
IPR002735. Transl_init_fac_IF2/IF5.
IPR016189. Transl_init_fac_IF2/IF5_N.
IPR016190. Transl_init_fac_IF2/IF5_Zn-bd.
IPR003307. W2_domain.
[Graphical view]
PfamiPF01873. eIF-5_eIF-2B. 1 hit.
PF02020. W2. 1 hit.
[Graphical view]
SMARTiSM00653. eIF2B_5. 1 hit.
SM00515. eIF5C. 1 hit.
[Graphical view]
SUPFAMiSSF100966. SSF100966. 1 hit.
SSF48371. SSF48371. 1 hit.
SSF75689. SSF75689. 1 hit.
PROSITEiPS51363. W2. 1 hit.
[Graphical view]
ProtoNetiSearch...

Publicationsi

« Hide 'large scale' publications
  1. "Characterization of multiple mRNAs that encode mammalian translation initiation factor 5 (eIF-5)."
    Si K., Das K., Maitra U.
    J. Biol. Chem. 271:16934-16938(1996) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [MRNA].
  2. Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA].
    Tissue: Brain.
  3. "Complete sequencing and characterization of 21,243 full-length human cDNAs."
    Ota T., Suzuki Y., Nishikawa T., Otsuki T., Sugiyama T., Irie R., Wakamatsu A., Hayashi K., Sato H., Nagai K., Kimura K., Makita H., Sekine M., Obayashi M., Nishi T., Shibahara T., Tanaka T., Ishii S.
    , Yamamoto J., Saito K., Kawai Y., Isono Y., Nakamura Y., Nagahari K., Murakami K., Yasuda T., Iwayanagi T., Wagatsuma M., Shiratori A., Sudo H., Hosoiri T., Kaku Y., Kodaira H., Kondo H., Sugawara M., Takahashi M., Kanda K., Yokoi T., Furuya T., Kikkawa E., Omura Y., Abe K., Kamihara K., Katsuta N., Sato K., Tanikawa M., Yamazaki M., Ninomiya K., Ishibashi T., Yamashita H., Murakawa K., Fujimori K., Tanai H., Kimata M., Watanabe M., Hiraoka S., Chiba Y., Ishida S., Ono Y., Takiguchi S., Watanabe S., Yosida M., Hotuta T., Kusano J., Kanehori K., Takahashi-Fujii A., Hara H., Tanase T.-O., Nomura Y., Togiya S., Komai F., Hara R., Takeuchi K., Arita M., Imose N., Musashino K., Yuuki H., Oshima A., Sasaki N., Aotsuka S., Yoshikawa Y., Matsunawa H., Ichihara T., Shiohata N., Sano S., Moriya S., Momiyama H., Satoh N., Takami S., Terashima Y., Suzuki O., Nakagawa S., Senoh A., Mizoguchi H., Goto Y., Shimizu F., Wakebe H., Hishigaki H., Watanabe T., Sugiyama A., Takemoto M., Kawakami B., Yamazaki M., Watanabe K., Kumagai A., Itakura S., Fukuzumi Y., Fujimori Y., Komiyama M., Tashiro H., Tanigami A., Fujiwara T., Ono T., Yamada K., Fujii Y., Ozaki K., Hirao M., Ohmori Y., Kawabata A., Hikiji T., Kobatake N., Inagaki H., Ikema Y., Okamoto S., Okitani R., Kawakami T., Noguchi S., Itoh T., Shigeta K., Senba T., Matsumura K., Nakajima Y., Mizuno T., Morinaga M., Sasaki M., Togashi T., Oyama M., Hata H., Watanabe M., Komatsu T., Mizushima-Sugano J., Satoh T., Shirai Y., Takahashi Y., Nakagawa K., Okumura K., Nagase T., Nomura N., Kikuchi H., Masuho Y., Yamashita R., Nakai K., Yada T., Nakamura Y., Ohara O., Isogai T., Sugano S.
    Nat. Genet. 36:40-45(2004) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA].
  4. Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA].
    Tissue: Testis.
  5. Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
  6. "The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC)."
    The MGC Project Team
    Genome Res. 14:2121-2127(2004) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA].
    Tissue: Brain and Uterus.
  7. "Kinase-selective enrichment enables quantitative phosphoproteomics of the kinome across the cell cycle."
    Daub H., Olsen J.V., Bairlein M., Gnad F., Oppermann F.S., Korner R., Greff Z., Keri G., Stemmann O., Mann M.
    Mol. Cell 31:438-448(2008) [PubMed] [Europe PMC] [Abstract]
    Cited for: IDENTIFICATION BY MASS SPECTROMETRY [LARGE SCALE ANALYSIS].
    Tissue: Cervix carcinoma.
  8. Cited for: PHOSPHORYLATION [LARGE SCALE ANALYSIS] AT SER-10; SER-229; SER-389; SER-390 AND SER-419, IDENTIFICATION BY MASS SPECTROMETRY [LARGE SCALE ANALYSIS].
    Tissue: Cervix carcinoma.
  9. "Lys-N and trypsin cover complementary parts of the phosphoproteome in a refined SCX-based approach."
    Gauci S., Helbig A.O., Slijper M., Krijgsveld J., Heck A.J., Mohammed S.
    Anal. Chem. 81:4493-4501(2009) [PubMed] [Europe PMC] [Abstract]
    Cited for: IDENTIFICATION BY MASS SPECTROMETRY [LARGE SCALE ANALYSIS].
  10. "Quantitative phosphoproteomic analysis of T cell receptor signaling reveals system-wide modulation of protein-protein interactions."
    Mayya V., Lundgren D.H., Hwang S.-I., Rezaul K., Wu L., Eng J.K., Rodionov V., Han D.K.
    Sci. Signal. 2:RA46-RA46(2009) [PubMed] [Europe PMC] [Abstract]
    Cited for: PHOSPHORYLATION [LARGE SCALE ANALYSIS] AT SER-389 AND SER-390, IDENTIFICATION BY MASS SPECTROMETRY [LARGE SCALE ANALYSIS].
    Tissue: Leukemic T-cell.
  11. "Quantitative phosphoproteomics reveals widespread full phosphorylation site occupancy during mitosis."
    Olsen J.V., Vermeulen M., Santamaria A., Kumar C., Miller M.L., Jensen L.J., Gnad F., Cox J., Jensen T.S., Nigg E.A., Brunak S., Mann M.
    Sci. Signal. 3:RA3-RA3(2010) [PubMed] [Europe PMC] [Abstract]
    Cited for: PHOSPHORYLATION [LARGE SCALE ANALYSIS] AT SER-10; SER-389; SER-390 AND SER-419, IDENTIFICATION BY MASS SPECTROMETRY [LARGE SCALE ANALYSIS].
    Tissue: Cervix carcinoma.
  12. Cited for: IDENTIFICATION BY MASS SPECTROMETRY [LARGE SCALE ANALYSIS].
  13. "System-wide temporal characterization of the proteome and phosphoproteome of human embryonic stem cell differentiation."
    Rigbolt K.T., Prokhorova T.A., Akimov V., Henningsen J., Johansen P.T., Kratchmarova I., Kassem M., Mann M., Olsen J.V., Blagoev B.
    Sci. Signal. 4:RS3-RS3(2011) [PubMed] [Europe PMC] [Abstract]
    Cited for: PHOSPHORYLATION [LARGE SCALE ANALYSIS] AT SER-389 AND SER-390, IDENTIFICATION BY MASS SPECTROMETRY [LARGE SCALE ANALYSIS].
  14. "Solution structure of the EIF-5_EIF-2B domain from human eukaryotic translation initiation factor 5."
    RIKEN structural genomics initiative (RSGI)
    Submitted (JAN-2008) to the PDB data bank
    Cited for: STRUCTURE BY NMR OF 1-150.
  15. Cited for: VARIANT [LARGE SCALE ANALYSIS] MET-418.

Entry informationi

Entry nameiIF5_HUMAN
AccessioniPrimary (citable) accession number: P55010
Secondary accession number(s): Q53XB3, Q9H5N2, Q9UG48
Entry historyi
Integrated into UniProtKB/Swiss-Prot: October 1, 1996
Last sequence update: January 10, 2003
Last modified: February 4, 2015
This is version 147 of the entry and version 2 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. Human chromosome 14
    Human chromosome 14: entries, gene names and cross-references to MIM
  2. Human entries with polymorphisms or disease mutations
    List of human entries with polymorphisms or disease mutations
  3. Human polymorphisms and disease mutations
    Index of human polymorphisms and disease mutations
  4. Translation initiation factors
    List of translation initiation factor entries
  5. MIM cross-references
    Online Mendelian Inheritance in Man (MIM) cross-references in UniProtKB/Swiss-Prot
  6. PDB cross-references
    Index of Protein Data Bank (PDB) cross-references
  7. 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.