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Protein

Cleavage and polyadenylation specificity factor subunit 4

Gene

CPSF4

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

Functioni

Component of the cleavage and polyadenylation specificity factor (CPSF) complex that play a key role in pre-mRNA 3'-end formation, recognizing the AAUAAA signal sequence and interacting with poly(A) polymerase and other factors to bring about cleavage and poly(A) addition. CPSF4 binds RNA polymers with a preference for poly(U).2 Publications

Regions

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Zinc fingeri35 – 6127C3H1-type 1PROSITE-ProRule annotationAdd
BLAST
Zinc fingeri62 – 8928C3H1-type 2PROSITE-ProRule annotationAdd
BLAST
Zinc fingeri90 – 11728C3H1-type 3PROSITE-ProRule annotationAdd
BLAST
Zinc fingeri118 – 14225C3H1-type 4PROSITE-ProRule annotationAdd
BLAST
Zinc fingeri143 – 16927C3H1-type 5PROSITE-ProRule annotationAdd
BLAST
Zinc fingeri243 – 26018CCHC-typePROSITE-ProRule annotationAdd
BLAST

GO - Molecular functioni

  • poly(A) RNA binding Source: UniProtKB
  • zinc ion binding Source: InterPro

GO - Biological processi

Complete GO annotation...

Keywords - Biological processi

Host-virus interaction, mRNA processing

Keywords - Ligandi

Metal-binding, RNA-binding, Zinc

Enzyme and pathway databases

ReactomeiREACT_6173. Inhibition of Host mRNA Processing and RNA Silencing.

Names & Taxonomyi

Protein namesi
Recommended name:
Cleavage and polyadenylation specificity factor subunit 4
Alternative name(s):
Cleavage and polyadenylation specificity factor 30 kDa subunit
Short name:
CPSF 30 kDa subunit
NS1 effector domain-binding protein 1
Short name:
Neb-1
No arches homolog
Gene namesi
Name:CPSF4
Synonyms:CPSF30, NAR, NEB1
OrganismiHomo sapiens (Human)
Taxonomic identifieri9606 [NCBI]
Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaEuarchontogliresPrimatesHaplorrhiniCatarrhiniHominidaeHomo
ProteomesiUP000005640 Componenti: Chromosome 7

Organism-specific databases

HGNCiHGNC:2327. CPSF4.

Subcellular locationi

GO - Cellular componenti

  • mRNA cleavage and polyadenylation specificity factor complex Source: UniProtKB
  • nucleoplasm Source: Reactome
Complete GO annotation...

Keywords - Cellular componenti

Nucleus

Pathology & Biotechi

Organism-specific databases

PharmGKBiPA26844.

Polymorphism and mutation databases

BioMutaiCPSF4.

PTM / Processingi

Molecule processing

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Chaini1 – 269269Cleavage and polyadenylation specificity factor subunit 4PRO_0000074402Add
BLAST

Amino acid modifications

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Modified residuei202 – 2021Phosphoserine2 Publications
Modified residuei212 – 2121Phosphoserine3 Publications

Keywords - PTMi

Phosphoprotein

Proteomic databases

MaxQBiO95639.
PaxDbiO95639.
PRIDEiO95639.

PTM databases

PhosphoSiteiO95639.

Expressioni

Gene expression databases

BgeeiO95639.
CleanExiHS_CPSF4.
ExpressionAtlasiO95639. baseline.
GenevisibleiO95639. HS.

Organism-specific databases

HPAiHPA049094.

Interactioni

Subunit structurei

Component of the cleavage and polyadenylation specificity factor (CPSF) complex, composed of CPSF1, CPSF2, CPSF3, CPSF4 and FIP1L1. Interacts with FIP1L1. Association with influenza A virus NS1 blocks processing of pre-mRNAs, thereby preventing nuclear export of host cell mRNAs.3 Publications

Binary interactionsi

WithEntry#Exp.IntActNotes
MEOX2A4D1273EBI-725860,EBI-10172134

Protein-protein interaction databases

BioGridi116104. 16 interactions.
DIPiDIP-48675N.
IntActiO95639. 8 interactions.
MINTiMINT-1429837.
STRINGi9606.ENSP00000292476.

Structurei

Secondary structure

1
269
Legend: HelixTurnBeta strand
Show more details
Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Helixi69 – 724Combined sources
Helixi79 – 813Combined sources
Beta strandi82 – 854Combined sources
Turni90 – 923Combined sources
Helixi97 – 1026Combined sources
Beta strandi111 – 1133Combined sources
Beta strandi122 – 1254Combined sources

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
EntryMethodResolution (Å)ChainPositionsPDBsum
2D9NNMR-A61-126[»]
2RHKX-ray1.95C/D61-121[»]
ProteinModelPortaliO95639.
SMRiO95639. Positions 61-126.
ModBaseiSearch...
MobiDBiSearch...

Miscellaneous databases

EvolutionaryTraceiO95639.

Family & Domainsi

Sequence similaritiesi

Belongs to the CPSF4/YTH1 family.Curated
Contains 5 C3H1-type zinc fingers.PROSITE-ProRule annotation
Contains 1 CCHC-type zinc finger.PROSITE-ProRule annotation

Zinc finger

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Zinc fingeri35 – 6127C3H1-type 1PROSITE-ProRule annotationAdd
BLAST
Zinc fingeri62 – 8928C3H1-type 2PROSITE-ProRule annotationAdd
BLAST
Zinc fingeri90 – 11728C3H1-type 3PROSITE-ProRule annotationAdd
BLAST
Zinc fingeri118 – 14225C3H1-type 4PROSITE-ProRule annotationAdd
BLAST
Zinc fingeri143 – 16927C3H1-type 5PROSITE-ProRule annotationAdd
BLAST
Zinc fingeri243 – 26018CCHC-typePROSITE-ProRule annotationAdd
BLAST

Keywords - Domaini

Repeat, Zinc-finger

Phylogenomic databases

eggNOGiCOG5084.
GeneTreeiENSGT00390000009627.
HOGENOMiHOG000212457.
HOVERGENiHBG051108.
InParanoidiO95639.
KOiK14404.
OMAiHYANKCT.
OrthoDBiEOG7XH6QD.
PhylomeDBiO95639.
TreeFamiTF314871.

Family and domain databases

Gene3Di4.10.1000.10. 2 hits.
4.10.60.10. 1 hit.
InterProiIPR000571. Znf_CCCH.
IPR001878. Znf_CCHC.
[Graphical view]
PfamiPF00642. zf-CCCH. 2 hits.
PF00098. zf-CCHC. 1 hit.
[Graphical view]
SMARTiSM00343. ZnF_C2HC. 1 hit.
SM00356. ZnF_C3H1. 5 hits.
[Graphical view]
SUPFAMiSSF57756. SSF57756. 1 hit.
PROSITEiPS50103. ZF_C3H1. 5 hits.
PS50158. ZF_CCHC. 1 hit.
[Graphical view]

Sequences (3)i

Sequence statusi: Complete.

This entry describes 3 isoformsi produced by alternative splicing. AlignAdd to basket

Isoform 1 (identifier: O95639-1) [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
MQEIIASVDH IKFDLEIAVE QQLGAQPLPF PGMDKSGAAV CEFFLKAACG
60 70 80 90 100
KGGMCPFRHI SGEKTVVCKH WLRGLCKKGD QCEFLHEYDM TKMPECYFYS
110 120 130 140 150
KFGECSNKEC PFLHIDPESK IKDCPWYDRG FCKHGPLCRH RHTRRVICVN
160 170 180 190 200
YLVGFCPEGP SCKFMHPRFE LPMGTTEQPP LPQQTQPPAK QSNNPPLQRS
210 220 230 240 250
SSLIQLTSQN SSPNQQRTPQ VIGVMQSQNS SAGNRGPRPL EQVTCYKCGE
260
KGHYANRCTK GHLAFLSGQ
Length:269
Mass (Da):30,255
Last modified:May 1, 1999 - v1
Checksum:i49444E3EB840464A
GO
Isoform 2 (identifier: O95639-2) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     191-215: Missing.

Note: No experimental confirmation available.
Show »
Length:244
Mass (Da):27,547
Checksum:i0DF72BE36CF97106
GO
Isoform 3 (identifier: O95639-3) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     191-216: Missing.

Note: May be due to a competing acceptor splice site. No experimental confirmation available.
Show »
Length:243
Mass (Da):27,419
Checksum:i3535FE5A0D525C8F
GO

Alternative sequence

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Alternative sequencei191 – 21626Missing in isoform 3. 1 PublicationVSP_008602Add
BLAST
Alternative sequencei191 – 21525Missing in isoform 2. 1 PublicationVSP_008601Add
BLAST

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
U79569 mRNA. Translation: AAD00321.1.
CR542161 mRNA. Translation: CAG46958.1.
EF191081 Genomic DNA. Translation: ABN05292.1.
CH236956 Genomic DNA. Translation: EAL23878.1.
CH471091 Genomic DNA. Translation: EAW76667.1.
CH471091 Genomic DNA. Translation: EAW76668.1.
BC003101 mRNA. Translation: AAH03101.1.
BC050738 mRNA. Translation: AAH50738.1.
CCDSiCCDS47652.1. [O95639-2]
CCDS5664.1. [O95639-1]
RefSeqiNP_001075028.1. NM_001081559.1. [O95639-2]
NP_006684.1. NM_006693.2. [O95639-1]
XP_011514060.1. XM_011515758.1. [O95639-3]
UniGeneiHs.489287.

Genome annotation databases

EnsembliENST00000292476; ENSP00000292476; ENSG00000160917.
ENST00000436336; ENSP00000395311; ENSG00000160917. [O95639-2]
GeneIDi10898.
KEGGihsa:10898.
UCSCiuc003uqi.3. human. [O95639-2]
uc003uqj.3. human. [O95639-1]
uc003uqk.3. human. [O95639-3]

Keywords - Coding sequence diversityi

Alternative splicing

Cross-referencesi

Web resourcesi

SeattleSNPs

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
U79569 mRNA. Translation: AAD00321.1.
CR542161 mRNA. Translation: CAG46958.1.
EF191081 Genomic DNA. Translation: ABN05292.1.
CH236956 Genomic DNA. Translation: EAL23878.1.
CH471091 Genomic DNA. Translation: EAW76667.1.
CH471091 Genomic DNA. Translation: EAW76668.1.
BC003101 mRNA. Translation: AAH03101.1.
BC050738 mRNA. Translation: AAH50738.1.
CCDSiCCDS47652.1. [O95639-2]
CCDS5664.1. [O95639-1]
RefSeqiNP_001075028.1. NM_001081559.1. [O95639-2]
NP_006684.1. NM_006693.2. [O95639-1]
XP_011514060.1. XM_011515758.1. [O95639-3]
UniGeneiHs.489287.

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
EntryMethodResolution (Å)ChainPositionsPDBsum
2D9NNMR-A61-126[»]
2RHKX-ray1.95C/D61-121[»]
ProteinModelPortaliO95639.
SMRiO95639. Positions 61-126.
ModBaseiSearch...
MobiDBiSearch...

Protein-protein interaction databases

BioGridi116104. 16 interactions.
DIPiDIP-48675N.
IntActiO95639. 8 interactions.
MINTiMINT-1429837.
STRINGi9606.ENSP00000292476.

PTM databases

PhosphoSiteiO95639.

Polymorphism and mutation databases

BioMutaiCPSF4.

Proteomic databases

MaxQBiO95639.
PaxDbiO95639.
PRIDEiO95639.

Protocols and materials databases

DNASUi10898.
Structural Biology KnowledgebaseSearch...

Genome annotation databases

EnsembliENST00000292476; ENSP00000292476; ENSG00000160917.
ENST00000436336; ENSP00000395311; ENSG00000160917. [O95639-2]
GeneIDi10898.
KEGGihsa:10898.
UCSCiuc003uqi.3. human. [O95639-2]
uc003uqj.3. human. [O95639-1]
uc003uqk.3. human. [O95639-3]

Organism-specific databases

CTDi10898.
GeneCardsiGC07P099036.
HGNCiHGNC:2327. CPSF4.
HPAiHPA049094.
MIMi603052. gene.
neXtProtiNX_O95639.
PharmGKBiPA26844.
GenAtlasiSearch...

Phylogenomic databases

eggNOGiCOG5084.
GeneTreeiENSGT00390000009627.
HOGENOMiHOG000212457.
HOVERGENiHBG051108.
InParanoidiO95639.
KOiK14404.
OMAiHYANKCT.
OrthoDBiEOG7XH6QD.
PhylomeDBiO95639.
TreeFamiTF314871.

Enzyme and pathway databases

ReactomeiREACT_6173. Inhibition of Host mRNA Processing and RNA Silencing.

Miscellaneous databases

EvolutionaryTraceiO95639.
GeneWikiiCPSF4.
GenomeRNAii10898.
NextBioi41385.
PROiO95639.
SOURCEiSearch...

Gene expression databases

BgeeiO95639.
CleanExiHS_CPSF4.
ExpressionAtlasiO95639. baseline.
GenevisibleiO95639. HS.

Family and domain databases

Gene3Di4.10.1000.10. 2 hits.
4.10.60.10. 1 hit.
InterProiIPR000571. Znf_CCCH.
IPR001878. Znf_CCHC.
[Graphical view]
PfamiPF00642. zf-CCCH. 2 hits.
PF00098. zf-CCHC. 1 hit.
[Graphical view]
SMARTiSM00343. ZnF_C2HC. 1 hit.
SM00356. ZnF_C3H1. 5 hits.
[Graphical view]
SUPFAMiSSF57756. SSF57756. 1 hit.
PROSITEiPS50103. ZF_C3H1. 5 hits.
PS50158. ZF_CCHC. 1 hit.
[Graphical view]
ProtoNetiSearch...

Publicationsi

« Hide 'large scale' publications
  1. "Assignment of the human homolog of the zebrafish essential gene no arches to 7q22.1."
    Kawakami K., Gaiano N., Grosshans D., Scherer S., Tsui L.-C., Hopkins N.
    Submitted (NOV-1996) to the EMBL/GenBank/DDBJ databases
    Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ISOFORM 1).
  2. "Cloning of human full open reading frames in Gateway(TM) system entry vector (pDONR201)."
    Halleck A., Ebert L., Mkoundinya M., Schick M., Eisenstein S., Neubert P., Kstrang K., Schatten R., Shen B., Henze S., Mar W., Korn B., Zuo D., Hu Y., LaBaer J.
    Submitted (JUN-2004) to the EMBL/GenBank/DDBJ databases
    Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA] (ISOFORM 1).
  3. SeattleSNPs variation discovery resource
    Submitted (DEC-2006) to the EMBL/GenBank/DDBJ databases
    Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA].
  4. "Human chromosome 7: DNA sequence and biology."
    Scherer S.W., Cheung J., MacDonald J.R., Osborne L.R., Nakabayashi K., Herbrick J.-A., Carson A.R., Parker-Katiraee L., Skaug J., Khaja R., Zhang J., Hudek A.K., Li M., Haddad M., Duggan G.E., Fernandez B.A., Kanematsu E., Gentles S.
    , Christopoulos C.C., Choufani S., Kwasnicka D., Zheng X.H., Lai Z., Nusskern D.R., Zhang Q., Gu Z., Lu F., Zeesman S., Nowaczyk M.J., Teshima I., Chitayat D., Shuman C., Weksberg R., Zackai E.H., Grebe T.A., Cox S.R., Kirkpatrick S.J., Rahman N., Friedman J.M., Heng H.H.Q., Pelicci P.G., Lo-Coco F., Belloni E., Shaffer L.G., Pober B., Morton C.C., Gusella J.F., Bruns G.A.P., Korf B.R., Quade B.J., Ligon A.H., Ferguson H., Higgins A.W., Leach N.T., Herrick S.R., Lemyre E., Farra C.G., Kim H.-G., Summers A.M., Gripp K.W., Roberts W., Szatmari P., Winsor E.J.T., Grzeschik K.-H., Teebi A., Minassian B.A., Kere J., Armengol L., Pujana M.A., Estivill X., Wilson M.D., Koop B.F., Tosi S., Moore G.E., Boright A.P., Zlotorynski E., Kerem B., Kroisel P.M., Petek E., Oscier D.G., Mould S.J., Doehner H., Doehner K., Rommens J.M., Vincent J.B., Venter J.C., Li P.W., Mural R.J., Adams M.D., Tsui L.-C.
    Science 300:767-772(2003) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
  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] (ISOFORMS 2 AND 3).
    Tissue: Eye and PNS.
  7. "The 30-kD subunit of mammalian cleavage and polyadenylation specificity factor and its yeast homolog are RNA-binding zinc finger proteins."
    Barabino S.M.L., Huebner W., Jenny A., Minvielle-Sebastia L., Keller W.
    Genes Dev. 11:1703-1716(1997) [PubMed] [Europe PMC] [Abstract]
    Cited for: FUNCTION.
  8. "Influenza virus NS1 protein interacts with the cellular 30 kDa subunit of CPSF and inhibits 3'end formation of cellular pre-mRNAs."
    Nemeroff M.E., Barabino S.M.L., Li Y., Keller W., Krug R.M.
    Mol. Cell 1:991-1000(1998) [PubMed] [Europe PMC] [Abstract]
    Cited for: INTERACTION WITH INFLUENZA A VIRUS NS1 PROTEIN.
  9. "Human Fip1 is a subunit of CPSF that binds to U-rich RNA elements and stimulates poly(A) polymerase."
    Kaufmann I., Martin G., Friedlein A., Langen H., Keller W.
    EMBO J. 23:616-626(2004) [PubMed] [Europe PMC] [Abstract]
    Cited for: FUNCTION IN PRE-MRNA 3'-END PROCESSING, IDENTIFICATION IN THE CPSF COMPLEX, INTERACTION WITH FIP1L1.
  10. Cited for: PHOSPHORYLATION [LARGE SCALE ANALYSIS] AT SER-202 AND SER-212, IDENTIFICATION BY MASS SPECTROMETRY [LARGE SCALE ANALYSIS].
    Tissue: Cervix carcinoma.
  11. "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].
  12. "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-202 AND SER-212, IDENTIFICATION BY MASS SPECTROMETRY [LARGE SCALE ANALYSIS].
    Tissue: Leukemic T-cell.
  13. "The poly A polymerase Star-PAP controls 3'-end cleavage by promoting CPSF interaction and specificity toward the pre-mRNA."
    Laishram R.S., Anderson R.A.
    EMBO J. 29:4132-4145(2010) [PubMed] [Europe PMC] [Abstract]
    Cited for: IDENTIFICATION IN THE CPSF COMPLEX.
  14. "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: IDENTIFICATION BY MASS SPECTROMETRY [LARGE SCALE ANALYSIS].
    Tissue: Cervix carcinoma.
  15. "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-212, IDENTIFICATION BY MASS SPECTROMETRY [LARGE SCALE ANALYSIS].
  16. "Solution structure of CCCH-type zinc-finger domain 2 in cleavage and polyadenylation specificity factor."
    RIKEN structural genomics initiative (RSGI)
    Submitted (JUN-2006) to the PDB data bank
    Cited for: STRUCTURE BY NMR OF 61-126.

Entry informationi

Entry nameiCPSF4_HUMAN
AccessioniPrimary (citable) accession number: O95639
Secondary accession number(s): D6W5S8
, Q6FGE6, Q86TF8, Q9BTW6
Entry historyi
Integrated into UniProtKB/Swiss-Prot: October 24, 2003
Last sequence update: May 1, 1999
Last modified: July 22, 2015
This is version 132 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

3D-structure, Complete proteome, Reference proteome

Documents

  1. Human chromosome 7
    Human chromosome 7: 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. PDB cross-references
    Index of Protein Data Bank (PDB) cross-references
  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.