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Protein

Src substrate cortactin

Gene

Cttn

Organism
Rattus norvegicus (Rat)
Status
Reviewed-Annotation score: Annotation score: 5 out of 5-Experimental evidence at protein leveli

Functioni

Contributes to the organization of the actin cytoskeleton and cell shape (PubMed:18768925). Plays a role in the formation of lamellipodia and in cell migration (PubMed:18768925). Plays a role in the regulation of neuron morphology, axon growth and formation of neuronal growth cones (PubMed:21210813). Through its interaction with CTTNBP2, involved in the regulation of neuronal spine density (By similarity). Plays a role in the invasiveness of cancer cells, and the formation of metastases (By similarity). Plays a role in focal adhesion assembly and turnover (PubMed:18768925, PubMed:22952866). In complex with ABL1 and MYLK regulates cortical actin-based cytoskeletal rearrangement critical to sphingosine 1-phosphate (S1P)-mediated endothelial cell (EC) barrier enhancement (By similarity). Plays a role in intracellular protein transport and endocytosis, and in modulating the levels of potassium channels present at the cell membrane (By similarity). Plays a role in receptor-mediated endocytosis via clathrin-coated pits (PubMed:12612086, PubMed:19995918).By similarity5 Publications

GO - Molecular functioni

  1. proline-rich region binding Source: RGD

GO - Biological processi

  1. actin cytoskeleton reorganization Source: UniProtKB
  2. brain development Source: RGD
  3. cell motility Source: UniProtKB
  4. focal adhesion assembly Source: UniProtKB
  5. intracellular protein transport Source: UniProtKB
  6. lamellipodium organization Source: UniProtKB
  7. neuron projection morphogenesis Source: UniProtKB
  8. positive regulation of actin filament polymerization Source: UniProtKB
  9. receptor-mediated endocytosis Source: UniProtKB
  10. regulation of axon extension Source: UniProtKB
Complete GO annotation...

Keywords - Biological processi

Endocytosis

Names & Taxonomyi

Protein namesi
Recommended name:
Src substrate cortactin
Gene namesi
Name:CttnImported
OrganismiRattus norvegicus (Rat)Imported
Taxonomic identifieri10116 [NCBI]
Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaEuarchontogliresGliresRodentiaSciurognathiMuroideaMuridaeMurinaeRattus
ProteomesiUP000002494: Chromosome 1

Organism-specific databases

RGDi619839. Cttn.

Subcellular locationi

Cytoplasmcytoskeleton By similarity. Cell projectionlamellipodium By similarity. Cell projectionruffle By similarity. Cytoplasmcell cortex 1 Publication. Cell projection 1 Publication. Cell projectionpodosome By similarity. Cell junction 1 Publication. Cell projectiondendritic spine By similarity. Cell projectiondendrite By similarity. Membraneclathrin-coated pit 2 Publications. Cell junctionfocal adhesion 2 Publications. Cell membrane 3 Publications; Peripheral membrane protein Curated; Cytoplasmic side Curated
Note: Colocalizes transiently with PTK2/FAK1 at focal adhesions (PubMed:22952866). Associated with membrane ruffles and lamellipodia. In the presence of CTTNBP2NL, colocalizes with stress fibers. In the presence of CTTNBP2, localizes at the cell cortex. In response to neuronal activation by glutamate, redistributes from dendritic spines to the dendritic shaft (By similarity). Colocalizes with DNM2 at the basis of filopodia in hippocampus neuron growth zones (PubMed:21210813).By similarity2 Publications

GO - Cellular componenti

  1. cell junction Source: UniProtKB
  2. coated pit Source: UniProtKB
  3. cortical cytoskeleton Source: UniProtKB
  4. lamellipodium Source: UniProtKB
  5. ruffle Source: InterPro
Complete GO annotation...

Keywords - Cellular componenti

Cell junction, Cell membrane, Cell projection, Coated pit, Cytoplasm, Cytoskeleton, Membrane

Pathology & Biotechi

Mutagenesis

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Mutagenesisi368 – 3681S → A: Inhibits actin polymerization; when associated with A-381. 1 Publication
Mutagenesisi381 – 3811S → A: Inhibits actin polymerization; when associated with A-368. 1 Publication
Mutagenesisi384 – 3841Y → E: Promotes reorganization of the actin cytoskeleton and cell motility; when associated with E-429 and E-445. 1 Publication
Mutagenesisi384 – 3841Y → F: Impairs receptor-mediated endocytosis. Increases the stability of focal adhesion and decreases their turnover; when associated with F-429 and F-445. 2 Publications
Mutagenesisi429 – 4291Y → E: Promotes reorganization of the actin cytoskeleton and cell motility; when associated with E-384 and E-445. 1 Publication
Mutagenesisi429 – 4291Y → F: Impairs receptor-mediated endocytosis. Increases the stability of focal adhesion and decreases their turnover; when associated with F-384 and F-445. 2 Publications
Mutagenesisi445 – 4451Y → E: Promotes reorganization of the actin cytoskeleton and cell motility; when associated with E-384 and E-429. 1 Publication
Mutagenesisi445 – 4451Y → F: Impairs receptor-mediated endocytosis. Increases the stability of focal adhesion and decreases their turnover; when associated with F-384 and F-429. 2 Publications

PTM / Processingi

Molecule processing

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Chaini1 – 509509Src substrate cortactinPRO_0000431700Add
BLAST

Amino acid modifications

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Modified residuei87 – 871N6-acetyllysineBy similarity
Modified residuei124 – 1241N6-acetyllysineBy similarity
Modified residuei144 – 1441N6-acetyllysineBy similarity
Modified residuei161 – 1611N6-acetyllysineBy similarity
Modified residuei181 – 1811N6-acetyllysineBy similarity
Modified residuei198 – 1981N6-acetyllysineBy similarity
Modified residuei235 – 2351N6-acetyllysineBy similarity
Modified residuei267 – 2671N6-acetyllysineBy similarity
Modified residuei272 – 2721N6-acetyllysineBy similarity
Modified residuei309 – 3091N6-acetyllysineBy similarity
Modified residuei364 – 3641PhosphothreonineBy similarity
Modified residuei368 – 3681PhosphoserineBy similarity
Modified residuei370 – 3701PhosphoserineBy similarity
Modified residuei380 – 3801PhosphoserineBy similarity
Modified residuei381 – 3811PhosphoserineBy similarity
Modified residuei384 – 3841Phosphotyrosine; by FAK11 Publication
Modified residuei405 – 4051PhosphotyrosineBy similarity
Modified residuei429 – 4291Phosphotyrosine; by FAK11 Publication
Modified residuei445 – 4451Phosphotyrosine; by FAK11 Publication
Modified residuei445 – 4451Phosphotyrosine; by SRCBy similarity
Modified residuei448 – 4481Phosphotyrosine; by SRCBy similarity

Post-translational modificationi

Phosphorylated by FER. Phosphorylated in response to FGR activation. Phosphorylation by SRC promotes MYLK binding (By similarity). Tyrosine phosphorylation in transformed cells may contribute to cellular growth regulation and transformation. Phosphorylated by PKN2 at both serine and threonine residues in a GTP-bound Rac1-dependent manner in hyaluronan-induced astrocytes and hence down-regulated CTTN ability to associate with filamentous actin (By similarity). Phosphorylated on tyrosine residues in response to CHRM1 activation (PubMed:12151401). Phosphorylated by PTK2/FAK1 in response to cell adhesion (PubMed:22952866).By similarity3 Publications

Keywords - PTMi

Acetylation, Phosphoprotein

Expressioni

Tissue specificityi

Detected in liver (at protein level).1 Publication

Gene expression databases

ExpressionAtlasiQ66HL2. baseline.
GenevestigatoriQ66HL2.

Interactioni

Subunit structurei

Interacts with SHANK2 and SHANK3 (via its SH3 domain). Interacts with PLXDC2 and SRCIN1. Interacts with SAMSN1 (via SH3 domain). Interacts (via SH3 domain) with ASAP1 (via Pro-rich region). Interacts with FER. Forms a complex with ABL1 and MYLK (By similarity). Interacts with FGD1. Identified in a complex containing FGFR4, NCAM1, CDH2, PLCG1, FRS2, SRC, SHC1, GAP43 and CTTN. Interacts with ABL2. Interacts with CTTNBP2NL; this interaction may target CTTN to stress fibers. Interacts with CTTNBP2; this interaction may target CTTN at the cell cortex or dendritic spines (By similarity). Interacts (via SH3 domain) with DNM2 (PubMed:21210813). Interacts with ACTN1 (PubMed:21210813). Interacts with KCNA2 (via non-phosphorylated C-terminus) (PubMed:12151401, PubMed:17959782). Interacts with PTK2/FAK1 (PubMed:22952866).By similarity4 Publications

Binary interactionsi

WithEntry#Exp.IntActNotes
Cfl1P455924EBI-6273816,EBI-917556

Structurei

3D structure databases

ProteinModelPortaliQ66HL2.
SMRiQ66HL2. Positions 444-509.
ModBaseiSearch...
MobiDBiSearch...

Family & Domainsi

Domains and Repeats

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Repeati80 – 11637Cortactin 1PROSITE-ProRule annotationAdd
BLAST
Repeati117 – 15337Cortactin 2PROSITE-ProRule annotationAdd
BLAST
Repeati154 – 19037Cortactin 3PROSITE-ProRule annotationAdd
BLAST
Repeati191 – 22737Cortactin 4PROSITE-ProRule annotationAdd
BLAST
Repeati228 – 26437Cortactin 5PROSITE-ProRule annotationAdd
BLAST
Repeati265 – 28723Cortactin 6; truncatedPROSITE-ProRule annotationAdd
BLAST
Domaini451 – 50959SH3PROSITE-ProRule annotationAdd
BLAST

Coiled coil

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Coiled coili311 – 36454Sequence AnalysisAdd
BLAST

Domaini

The SH3 motif may mediate binding to the cytoskeleton.Curated

Sequence similaritiesi

Contains 6 cortactin repeats.PROSITE-ProRule annotation
Contains 1 SH3 domain.PROSITE-ProRule annotation

Keywords - Domaini

Coiled coil, Repeat, SH3 domain

Phylogenomic databases

GeneTreeiENSGT00530000062953.
HOGENOMiHOG000006523.
HOVERGENiHBG005994.
KOiK06106.
OMAiHESQQDY.
OrthoDBiEOG7V49ZC.
PhylomeDBiQ66HL2.
TreeFamiTF318935.

Family and domain databases

InterProiIPR015503. Cortactin.
IPR003134. Hs1_Cortactin.
IPR001452. SH3_domain.
[Graphical view]
PANTHERiPTHR10829:SF15. PTHR10829:SF15. 1 hit.
PfamiPF02218. HS1_rep. 6 hits.
PF14604. SH3_9. 1 hit.
[Graphical view]
PRINTSiPR00452. SH3DOMAIN.
SMARTiSM00326. SH3. 1 hit.
[Graphical view]
SUPFAMiSSF50044. SSF50044. 2 hits.
PROSITEiPS51090. CORTACTIN. 6 hits.
PS50002. SH3. 1 hit.
[Graphical view]

Sequencei

Sequence statusi: Complete.

Q66HL2-1 [UniParc]FASTAAdd to Basket

« Hide

        10         20         30         40         50
MWKASAGHAV SITQDDGGAD DWETDPDFVN DVSEKEQRWG AKTVQGSGHQ
60 70 80 90 100
EHINIHKLRE NVFQEHQTLK EKELETGPKA SHGYGGKFGV EQDRMDKSAV
110 120 130 140 150
GHEYQSKLSK HCSQVDSVRG FGGKFGVQMD RVDQSAVGFE YQGKTEKHAS
160 170 180 190 200
QKDYSSGFGG KYGVQADRVD KSAVGFDYQG KTEKHESQKD YSKGFGGKYG
210 220 230 240 250
IDKDKVDKSA VGFEYQGKTE KHESQKDYVK GFGGKFGVQT DRQDKCALGW
260 270 280 290 300
DHQEKLQLHE SQKDYAKGFG GKYGVQKDRM DKNASTFEEV VQVPSAYQKT
310 320 330 340 350
VPIEAVTSKT SNIRANFENL AKEREQEDRR KAEAERAQRM AQERQEQEEA
360 370 380 390 400
RRKLEEQARA KKQTPPASPS PQPAEDRPPS SPIYEDAAPL KAEPSYGSSE
410 420 430 440 450
PEPEYSTEAA GLPEASNQQG LAYTSEPVYE TTEVPGHYQA EDDTYDGYES
460 470 480 490 500
DLGITAIALY DYQAAGDDEI SFDPDDVITN IEMIDDGWWR GVCKGRYGLF

PANYVELRQ
Length:509
Mass (Da):56,942
Last modified:October 11, 2004 - v1
Checksum:i059CDB52681E2592
GO

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
AABR06009380 Genomic DNA. No translation available.
AABR06009448 Genomic DNA. No translation available.
CH473953 Genomic DNA. Translation: EDM12238.1.
BC081802 mRNA. Translation: AAH81802.1.
RefSeqiNP_068640.2. NM_021868.2.
UniGeneiRn.107869.

Genome annotation databases

EnsembliENSRNOT00000028283; ENSRNOP00000028283; ENSRNOG00000050994.
ENSRNOT00000054859; ENSRNOP00000051742; ENSRNOG00000047280.
GeneIDi60465.
KEGGirno:60465.
UCSCiRGD:619839. rat.

Cross-referencesi

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
AABR06009380 Genomic DNA. No translation available.
AABR06009448 Genomic DNA. No translation available.
CH473953 Genomic DNA. Translation: EDM12238.1.
BC081802 mRNA. Translation: AAH81802.1.
RefSeqiNP_068640.2. NM_021868.2.
UniGeneiRn.107869.

3D structure databases

ProteinModelPortaliQ66HL2.
SMRiQ66HL2. Positions 444-509.
ModBaseiSearch...
MobiDBiSearch...

Protocols and materials databases

Structural Biology KnowledgebaseSearch...

Genome annotation databases

EnsembliENSRNOT00000028283; ENSRNOP00000028283; ENSRNOG00000050994.
ENSRNOT00000054859; ENSRNOP00000051742; ENSRNOG00000047280.
GeneIDi60465.
KEGGirno:60465.
UCSCiRGD:619839. rat.

Organism-specific databases

CTDi2017.
RGDi619839. Cttn.

Phylogenomic databases

GeneTreeiENSGT00530000062953.
HOGENOMiHOG000006523.
HOVERGENiHBG005994.
KOiK06106.
OMAiHESQQDY.
OrthoDBiEOG7V49ZC.
PhylomeDBiQ66HL2.
TreeFamiTF318935.

Miscellaneous databases

NextBioi35569564.
PROiQ66HL2.

Gene expression databases

ExpressionAtlasiQ66HL2. baseline.
GenevestigatoriQ66HL2.

Family and domain databases

InterProiIPR015503. Cortactin.
IPR003134. Hs1_Cortactin.
IPR001452. SH3_domain.
[Graphical view]
PANTHERiPTHR10829:SF15. PTHR10829:SF15. 1 hit.
PfamiPF02218. HS1_rep. 6 hits.
PF14604. SH3_9. 1 hit.
[Graphical view]
PRINTSiPR00452. SH3DOMAIN.
SMARTiSM00326. SH3. 1 hit.
[Graphical view]
SUPFAMiSSF50044. SSF50044. 2 hits.
PROSITEiPS51090. CORTACTIN. 6 hits.
PS50002. SH3. 1 hit.
[Graphical view]
ProtoNetiSearch...

Publicationsi

« Hide 'large scale' publications
  1. "Genome sequence of the Brown Norway rat yields insights into mammalian evolution."
    Gibbs R.A., Weinstock G.M., Metzker M.L., Muzny D.M., Sodergren E.J., Scherer S., Scott G., Steffen D., Worley K.C., Burch P.E., Okwuonu G., Hines S., Lewis L., Deramo C., Delgado O., Dugan-Rocha S., Miner G., Morgan M.
    , Hawes A., Gill R., Holt R.A., Adams M.D., Amanatides P.G., Baden-Tillson H., Barnstead M., Chin S., Evans C.A., Ferriera S., Fosler C., Glodek A., Gu Z., Jennings D., Kraft C.L., Nguyen T., Pfannkoch C.M., Sitter C., Sutton G.G., Venter J.C., Woodage T., Smith D., Lee H.-M., Gustafson E., Cahill P., Kana A., Doucette-Stamm L., Weinstock K., Fechtel K., Weiss R.B., Dunn D.M., Green E.D., Blakesley R.W., Bouffard G.G., De Jong P.J., Osoegawa K., Zhu B., Marra M., Schein J., Bosdet I., Fjell C., Jones S., Krzywinski M., Mathewson C., Siddiqui A., Wye N., McPherson J., Zhao S., Fraser C.M., Shetty J., Shatsman S., Geer K., Chen Y., Abramzon S., Nierman W.C., Havlak P.H., Chen R., Durbin K.J., Egan A., Ren Y., Song X.-Z., Li B., Liu Y., Qin X., Cawley S., Cooney A.J., D'Souza L.M., Martin K., Wu J.Q., Gonzalez-Garay M.L., Jackson A.R., Kalafus K.J., McLeod M.P., Milosavljevic A., Virk D., Volkov A., Wheeler D.A., Zhang Z., Bailey J.A., Eichler E.E., Tuzun E., Birney E., Mongin E., Ureta-Vidal A., Woodwark C., Zdobnov E., Bork P., Suyama M., Torrents D., Alexandersson M., Trask B.J., Young J.M., Huang H., Wang H., Xing H., Daniels S., Gietzen D., Schmidt J., Stevens K., Vitt U., Wingrove J., Camara F., Mar Alba M., Abril J.F., Guigo R., Smit A., Dubchak I., Rubin E.M., Couronne O., Poliakov A., Huebner N., Ganten D., Goesele C., Hummel O., Kreitler T., Lee Y.-A., Monti J., Schulz H., Zimdahl H., Himmelbauer H., Lehrach H., Jacob H.J., Bromberg S., Gullings-Handley J., Jensen-Seaman M.I., Kwitek A.E., Lazar J., Pasko D., Tonellato P.J., Twigger S., Ponting C.P., Duarte J.M., Rice S., Goodstadt L., Beatson S.A., Emes R.D., Winter E.E., Webber C., Brandt P., Nyakatura G., Adetobi M., Chiaromonte F., Elnitski L., Eswara P., Hardison R.C., Hou M., Kolbe D., Makova K., Miller W., Nekrutenko A., Riemer C., Schwartz S., Taylor J., Yang S., Zhang Y., Lindpaintner K., Andrews T.D., Caccamo M., Clamp M., Clarke L., Curwen V., Durbin R.M., Eyras E., Searle S.M., Cooper G.M., Batzoglou S., Brudno M., Sidow A., Stone E.A., Payseur B.A., Bourque G., Lopez-Otin C., Puente X.S., Chakrabarti K., Chatterji S., Dewey C., Pachter L., Bray N., Yap V.B., Caspi A., Tesler G., Pevzner P.A., Haussler D., Roskin K.M., Baertsch R., Clawson H., Furey T.S., Hinrichs A.S., Karolchik D., Kent W.J., Rosenbloom K.R., Trumbower H., Weirauch M., Cooper D.N., Stenson P.D., Ma B., Brent M., Arumugam M., Shteynberg D., Copley R.R., Taylor M.S., Riethman H., Mudunuri U., Peterson J., Guyer M., Felsenfeld A., Old S., Mockrin S., Collins F.S.
    Nature 428:493-521(2004) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
    Strain: Brown Norway.
  2. Mural R.J., Adams M.D., Myers E.W., Smith H.O., Venter J.C.
    Submitted (JUL-2005) to the EMBL/GenBank/DDBJ databases
    Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
    Strain: Brown Norway.
  3. "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: Kidney.
  4. "Cortactin is a component of clathrin-coated pits and participates in receptor-mediated endocytosis."
    Cao H., Orth J.D., Chen J., Weller S.G., Heuser J.E., McNiven M.A.
    Mol. Cell. Biol. 23:2162-2170(2003) [PubMed] [Europe PMC] [Abstract]
    Cited for: FUNCTION, SUBCELLULAR LOCATION, TISSUE SPECIFICITY.
  5. "Tyrosine phosphorylation of Kv1.2 modulates its interaction with the actin-binding protein cortactin."
    Hattan D., Nesti E., Cachero T.G., Morielli A.D.
    J. Biol. Chem. 277:38596-38606(2002) [PubMed] [Europe PMC] [Abstract]
    Cited for: INTERACTION WITH KCNA2.
  6. "An essential role for cortactin in the modulation of the potassium channel Kv1.2."
    Williams M.R., Markey J.C., Doczi M.A., Morielli A.D.
    Proc. Natl. Acad. Sci. U.S.A. 104:17412-17417(2007) [PubMed] [Europe PMC] [Abstract]
    Cited for: INTERACTION WITH KCNA2.
  7. "Distinct phospho-forms of cortactin differentially regulate actin polymerization and focal adhesions."
    Kruchten A.E., Krueger E.W., Wang Y., McNiven M.A.
    Am. J. Physiol. 295:C1113-C1122(2008) [PubMed] [Europe PMC] [Abstract]
    Cited for: FUNCTION, MUTAGENESIS OF SER-368; SER-381; TYR-384; TYR-429 AND TYR-445.
  8. "SRC-mediated phosphorylation of dynamin and cortactin regulates the 'constitutive' endocytosis of transferrin."
    Cao H., Chen J., Krueger E.W., McNiven M.A.
    Mol. Cell. Biol. 30:781-792(2010) [PubMed] [Europe PMC] [Abstract]
    Cited for: FUNCTION, SUBCELLULAR LOCATION, PHOSPHORYLATION, MUTAGENESIS OF TYR-384; TYR-429 AND TYR-445.
  9. "Growth cone morphology and spreading are regulated by a dynamin-cortactin complex at point contacts in hippocampal neurons."
    Kurklinsky S., Chen J., McNiven M.A.
    J. Neurochem. 117:48-60(2011) [PubMed] [Europe PMC] [Abstract]
    Cited for: FUNCTION, SUBCELLULAR LOCATION, INTERACTION WITH DNM2 AND ACTN1.
  10. "Cortactin as a target for FAK in the regulation of focal adhesion dynamics."
    Tomar A., Lawson C., Ghassemian M., Schlaepfer D.D.
    PLoS ONE 7:E44041-E44041(2012) [PubMed] [Europe PMC] [Abstract]
    Cited for: FUNCTION, INTERACTION WITH PTK2, PHOSPHORYLATION AT TYR-384 ANT TYR-429, SUBCELLULAR LOCATION, IDENTIFICATION BY MASS SPECTROMETRY, MUTAGENESIS OF TYR-384; TYR-429 AND TYR-445.

Entry informationi

Entry nameiSRC8_RAT
AccessioniPrimary (citable) accession number: Q66HL2
Secondary accession number(s): D3ZRB0
Entry historyi
Integrated into UniProtKB/Swiss-Prot: February 4, 2015
Last sequence update: October 11, 2004
Last modified: February 4, 2015
This is version 94 of the entry and version 1 of the sequence. [Complete history]
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programChordata Protein Annotation Program

Miscellaneousi

Keywords - Technical termi

Complete proteome, Reference proteome

Documents

  1. 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.