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Protein

ATP-dependent RNA helicase DDX19B

Gene

DDX19B

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

Functioni

ATP-dependent RNA helicase involved in mRNA export from the nucleus. Rather than unwinding RNA duplexes, DDX19B functions as a remodeler of ribonucleoprotein particles, whereby proteins bound to nuclear mRNA are dissociated and replaced by cytoplasmic mRNA binding proteins.

Catalytic activityi

ATP + H2O = ADP + phosphate.

Sites

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Binding sitei119ATP1
Binding sitei429ATP1
Binding sitei432ATP1

Regions

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Nucleotide bindingi138 – 145ATP8

GO - Molecular functioni

  • ATP binding Source: UniProtKB-KW
  • ATP-dependent RNA helicase activity Source: GO_Central
  • helicase activity Source: ProtInc
  • RNA binding Source: ProtInc

GO - Biological processi

  • mRNA export from nucleus Source: ProtInc
  • protein transport Source: UniProtKB-KW
  • RNA secondary structure unwinding Source: GO_Central
Complete GO annotation...

Keywords - Molecular functioni

Helicase, Hydrolase

Keywords - Biological processi

mRNA transport, Protein transport, Translocation, Transport

Keywords - Ligandi

ATP-binding, Nucleotide-binding, RNA-binding

Enzyme and pathway databases

BioCyciZFISH:ENSG00000157349-MONOMER.
BRENDAi3.6.4.13. 2681.

Protein family/group databases

TCDBi1.I.1.1.3. the nuclear pore complex (npc) family.

Names & Taxonomyi

Protein namesi
Recommended name:
ATP-dependent RNA helicase DDX19B (EC:3.6.4.13)
Alternative name(s):
DEAD box RNA helicase DEAD5
DEAD box protein 19B
Gene namesi
Name:DDX19B
Synonyms:DBP5, DDX19, TDBP
OrganismiHomo sapiens (Human)
Taxonomic identifieri9606 [NCBI]
Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaEuarchontogliresPrimatesHaplorrhiniCatarrhiniHominidaeHomo
Proteomesi
  • UP000005640 Componenti: Chromosome 16

Organism-specific databases

HGNCiHGNC:2742. DDX19B.

Subcellular locationi

GO - Cellular componenti

  • cytoplasm Source: HPA
  • extracellular exosome Source: UniProtKB
  • membrane Source: UniProtKB
  • nuclear envelope Source: UniProtKB
  • nuclear membrane Source: UniProtKB-SubCell
  • nuclear pore Source: ProtInc
  • nucleus Source: HPA
Complete GO annotation...

Keywords - Cellular componenti

Cytoplasm, Membrane, Nuclear pore complex, Nucleus

Pathology & Biotechi

Mutagenesis

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Mutagenesisi223D → R: Impairs interaction with NUP214 and RNA. 1 Publication1
Mutagenesisi243E → Q: Loss of activity. 1 Publication1
Mutagenesisi258I → A: Impairs interaction with NUP214. 1 Publication1
Mutagenesisi259R → D: Impairs interaction with NUP214. 1 Publication1
Mutagenesisi262R → A: Impairs interaction with NUP214. 1 Publication1

Organism-specific databases

OpenTargetsiENSG00000157349.
PharmGKBiPA27208.

Polymorphism and mutation databases

BioMutaiDDX19B.
DMDMi10719979.

PTM / Processingi

Molecule processing

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Initiator methionineiRemovedCombined sources
ChainiPRO_00000550222 – 479ATP-dependent RNA helicase DDX19BAdd BLAST478

Amino acid modifications

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Modified residuei2N-acetylalanineCombined sources1

Keywords - PTMi

Acetylation

Proteomic databases

EPDiQ9UMR2.
PaxDbiQ9UMR2.
PeptideAtlasiQ9UMR2.
PRIDEiQ9UMR2.

PTM databases

iPTMnetiQ9UMR2.
PhosphoSitePlusiQ9UMR2.

Expressioni

Gene expression databases

BgeeiENSG00000157349.
CleanExiHS_DDX19B.
ExpressionAtlasiQ9UMR2. baseline and differential.
GenevisibleiQ9UMR2. HS.

Organism-specific databases

HPAiCAB037229.
CAB037284.
HPA046380.
HPA066668.

Interactioni

Subunit structurei

Interacts with NUP214 or RNA in a mutually exclusive manner.3 Publications

Binary interactionsi

WithEntry#Exp.IntActNotes
MIF4GDA9UHW63EBI-719232,EBI-373498
TERF1P542742EBI-719232,EBI-710997

Protein-protein interaction databases

BioGridi116426. 110 interactors.
DIPiDIP-48486N.
IntActiQ9UMR2. 19 interactors.
MINTiMINT-4831823.
STRINGi9606.ENSP00000288071.

Structurei

Secondary structure

1479
Legend: HelixTurnBeta strandPDB Structure known for this area
Show more details
Feature keyPosition(s)DescriptionActionsGraphical viewLength
Helixi56 – 66Combined sources11
Helixi67 – 70Combined sources4
Helixi76 – 80Combined sources5
Beta strandi82 – 86Combined sources5
Helixi95 – 97Combined sources3
Helixi101 – 109Combined sources9
Helixi117 – 127Combined sources11
Beta strandi128 – 130Combined sources3
Beta strandi134 – 137Combined sources4
Helixi144 – 155Combined sources12
Beta strandi165 – 168Combined sources4
Helixi172 – 185Combined sources14
Turni186 – 188Combined sources3
Beta strandi194 – 197Combined sources4
Beta strandi212 – 216Combined sources5
Helixi218 – 225Combined sources8
Turni226 – 228Combined sources3
Helixi233 – 235Combined sources3
Beta strandi238 – 242Combined sources5
Helixi244 – 248Combined sources5
Turni250 – 253Combined sources4
Helixi254 – 262Combined sources9
Beta strandi269 – 275Combined sources7
Helixi279 – 288Combined sources10
Beta strandi289 – 291Combined sources3
Beta strandi293 – 295Combined sources3
Helixi299 – 301Combined sources3
Helixi304 – 306Combined sources3
Beta strandi307 – 313Combined sources7
Helixi317 – 331Combined sources15
Beta strandi332 – 339Combined sources8
Helixi343 – 355Combined sources13
Beta strandi361 – 363Combined sources3
Helixi369 – 380Combined sources12
Beta strandi385 – 389Combined sources5
Helixi391 – 393Combined sources3
Beta strandi394 – 396Combined sources3
Beta strandi402 – 409Combined sources8
Beta strandi414 – 418Combined sources5
Helixi420 – 427Combined sources8
Beta strandi437 – 443Combined sources7
Helixi446 – 459Combined sources14

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
PDB entryMethodResolution (Å)ChainPositionsPDBsum
3EWSX-ray2.70A/B54-475[»]
3FHCX-ray2.80B68-302[»]
3FHTX-ray2.20A/B68-479[»]
3FMOX-ray2.51B1-300[»]
3FMPX-ray3.19B/D1-479[»]
3G0HX-ray2.70A54-475[»]
ProteinModelPortaliQ9UMR2.
SMRiQ9UMR2.
ModBaseiSearch...
MobiDBiSearch...

Miscellaneous databases

EvolutionaryTraceiQ9UMR2.

Family & Domainsi

Domains and Repeats

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Domaini125 – 295Helicase ATP-bindingPROSITE-ProRule annotationAdd BLAST171
Domaini306 – 474Helicase C-terminalPROSITE-ProRule annotationAdd BLAST169

Region

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Regioni2 – 300N-terminal lobeAdd BLAST299
Regioni55 – 68N-terminal helixAdd BLAST14
Regioni301 – 479C-terminal lobeAdd BLAST179

Motif

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Motifi92 – 120Q motifAdd BLAST29
Motifi242 – 245DEAD box4

Domaini

The N-terminal extension helix acts as an autoinhibitory domain, preventing ATP hydrolysis, unless the N-terminus of the protein is displaced by RNA binding, allowing cleft closure to bring key side chains into position for catalysis.

Sequence similaritiesi

Contains 1 helicase ATP-binding domain.PROSITE-ProRule annotation
Contains 1 helicase C-terminal domain.PROSITE-ProRule annotation

Phylogenomic databases

eggNOGiKOG0332. Eukaryota.
ENOG410XRGX. LUCA.
GeneTreeiENSGT00530000063236.
HOGENOMiHOG000268797.
HOVERGENiHBG107989.
InParanoidiQ9UMR2.
KOiK18655.
PhylomeDBiQ9UMR2.
TreeFamiTF314957.

Family and domain databases

Gene3Di3.40.50.300. 2 hits.
InterProiIPR011545. DEAD/DEAH_box_helicase_dom.
IPR014001. Helicase_ATP-bd.
IPR001650. Helicase_C.
IPR027417. P-loop_NTPase.
IPR014014. RNA_helicase_DEAD_Q_motif.
[Graphical view]
PfamiPF00270. DEAD. 1 hit.
PF00271. Helicase_C. 1 hit.
[Graphical view]
SMARTiSM00487. DEXDc. 1 hit.
SM00490. HELICc. 1 hit.
[Graphical view]
SUPFAMiSSF52540. SSF52540. 1 hit.
PROSITEiPS51192. HELICASE_ATP_BIND_1. 1 hit.
PS51194. HELICASE_CTER. 1 hit.
PS51195. Q_MOTIF. 1 hit.
[Graphical view]

Sequences (4)i

Sequence statusi: Complete.

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

This entry describes 4 isoformsi produced by alternative splicing. AlignAdd to basket

Isoform 1 (identifier: Q9UMR2-1) [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
MATDSWALAV DEQEAAAESL SNLHLKEEKI KPDTNGAVVK TNANAEKTDE
60 70 80 90 100
EEKEDRAAQS LLNKLIRSNL VDNTNQVEVL QRDPNSPLYS VKSFEELRLK
110 120 130 140 150
PQLLQGVYAM GFNRPSKIQE NALPLMLAEP PQNLIAQSQS GTGKTAAFVL
160 170 180 190 200
AMLSQVEPAN KYPQCLCLSP TYELALQTGK VIEQMGKFYP ELKLAYAVRG
210 220 230 240 250
NKLERGQKIS EQIVIGTPGT VLDWCSKLKF IDPKKIKVFV LDEADVMIAT
260 270 280 290 300
QGHQDQSIRI QRMLPRNCQM LLFSATFEDS VWKFAQKVVP DPNVIKLKRE
310 320 330 340 350
EETLDTIKQY YVLCSSRDEK FQALCNLYGA ITIAQAMIFC HTRKTASWLA
360 370 380 390 400
AELSKEGHQV ALLSGEMMVE QRAAVIERFR EGKEKVLVTT NVCARGIDVE
410 420 430 440 450
QVSVVINFDL PVDKDGNPDN ETYLHRIGRT GRFGKRGLAV NMVDSKHSMN
460 470
ILNRIQEHFN KKIERLDTDD LDEIEKIAN
Length:479
Mass (Da):53,927
Last modified:May 1, 2000 - v1
Checksum:i8F6F93B12B7E9871
GO
Isoform 2 (identifier: Q9UMR2-2) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     100-130: Missing.

Show »
Length:448
Mass (Da):50,490
Checksum:i178321CBF4CA276A
GO
Isoform 3 (identifier: Q9UMR2-3) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     1-109: Missing.

Show »
Length:370
Mass (Da):41,779
Checksum:iA268A0E259FCF3E2
GO
Isoform 4 (identifier: Q9UMR2-4) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     1-19: MATDSWALAVDEQEAAAES → MAGAAGRVQDRALRRFPITLPVGD
     100-130: Missing.

Note: No experimental confirmation available.
Show »
Length:453
Mass (Da):51,063
Checksum:i6D543611ED7E4BFE
GO

Experimental Info

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Sequence conflicti128A → V in CAG33496 (Ref. 4) Curated1
Sequence conflicti201N → Y in BAG63488 (PubMed:14702039).Curated1
Sequence conflicti331I → T in CAG33496 (Ref. 4) Curated1
Sequence conflicti367M → V in CAG38540 (Ref. 4) Curated1

Natural variant

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Natural variantiVAR_052160149V → L.Corresponds to variant rs34607244dbSNPEnsembl.1

Alternative sequence

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Alternative sequenceiVSP_0413471 – 109Missing in isoform 3. 3 PublicationsAdd BLAST109
Alternative sequenceiVSP_0447271 – 19MATDS…AAAES → MAGAAGRVQDRALRRFPITL PVGD in isoform 4. 1 PublicationAdd BLAST19
Alternative sequenceiVSP_015239100 – 130Missing in isoform 2 and isoform 4. 3 PublicationsAdd BLAST31

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
AJ237946 mRNA. Translation: CAB52189.1.
AF353720 mRNA. Translation: AAK40102.1.
AL136639 mRNA. Translation: CAB66574.1.
CR457215 mRNA. Translation: CAG33496.1.
CR533509 mRNA. Translation: CAG38540.1.
AK027378 mRNA. Translation: BAG51311.1.
AK301938 mRNA. Translation: BAG63358.1.
AK302107 mRNA. Translation: BAG63488.1.
AK316346 mRNA. Translation: BAH14717.1.
AC012184 Genomic DNA. No translation available.
CH471241 Genomic DNA. Translation: EAW51827.1.
CH471241 Genomic DNA. Translation: EAW51831.1.
CH471241 Genomic DNA. Translation: EAW51832.1.
CH471241 Genomic DNA. Translation: EAW51834.1.
BC003626 mRNA. Translation: AAH03626.1.
BC010008 mRNA. Translation: AAH10008.1.
CCDSiCCDS10888.1. [Q9UMR2-1]
CCDS32475.1. [Q9UMR2-2]
CCDS42187.1. [Q9UMR2-3]
CCDS58478.1. [Q9UMR2-4]
RefSeqiNP_001014449.1. NM_001014449.2. [Q9UMR2-3]
NP_001014451.1. NM_001014451.2. [Q9UMR2-2]
NP_001244101.1. NM_001257172.1. [Q9UMR2-4]
NP_001244102.1. NM_001257173.1. [Q9UMR2-3]
NP_001244103.1. NM_001257174.1. [Q9UMR2-3]
NP_009173.1. NM_007242.5. [Q9UMR2-1]
XP_006721190.1. XM_006721127.2. [Q9UMR2-3]
XP_016878379.1. XM_017022890.1. [Q9UMR2-3]
UniGeneiHs.221761.

Genome annotation databases

EnsembliENST00000288071; ENSP00000288071; ENSG00000157349. [Q9UMR2-1]
ENST00000355992; ENSP00000348271; ENSG00000157349. [Q9UMR2-2]
ENST00000393657; ENSP00000377267; ENSG00000157349. [Q9UMR2-3]
ENST00000451014; ENSP00000392639; ENSG00000157349. [Q9UMR2-4]
ENST00000563392; ENSP00000456574; ENSG00000157349. [Q9UMR2-3]
ENST00000568625; ENSP00000456757; ENSG00000157349. [Q9UMR2-3]
GeneIDi11269.
KEGGihsa:11269.
UCSCiuc002eyo.5. human. [Q9UMR2-1]

Keywords - Coding sequence diversityi

Alternative splicing, Polymorphism

Cross-referencesi

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
AJ237946 mRNA. Translation: CAB52189.1.
AF353720 mRNA. Translation: AAK40102.1.
AL136639 mRNA. Translation: CAB66574.1.
CR457215 mRNA. Translation: CAG33496.1.
CR533509 mRNA. Translation: CAG38540.1.
AK027378 mRNA. Translation: BAG51311.1.
AK301938 mRNA. Translation: BAG63358.1.
AK302107 mRNA. Translation: BAG63488.1.
AK316346 mRNA. Translation: BAH14717.1.
AC012184 Genomic DNA. No translation available.
CH471241 Genomic DNA. Translation: EAW51827.1.
CH471241 Genomic DNA. Translation: EAW51831.1.
CH471241 Genomic DNA. Translation: EAW51832.1.
CH471241 Genomic DNA. Translation: EAW51834.1.
BC003626 mRNA. Translation: AAH03626.1.
BC010008 mRNA. Translation: AAH10008.1.
CCDSiCCDS10888.1. [Q9UMR2-1]
CCDS32475.1. [Q9UMR2-2]
CCDS42187.1. [Q9UMR2-3]
CCDS58478.1. [Q9UMR2-4]
RefSeqiNP_001014449.1. NM_001014449.2. [Q9UMR2-3]
NP_001014451.1. NM_001014451.2. [Q9UMR2-2]
NP_001244101.1. NM_001257172.1. [Q9UMR2-4]
NP_001244102.1. NM_001257173.1. [Q9UMR2-3]
NP_001244103.1. NM_001257174.1. [Q9UMR2-3]
NP_009173.1. NM_007242.5. [Q9UMR2-1]
XP_006721190.1. XM_006721127.2. [Q9UMR2-3]
XP_016878379.1. XM_017022890.1. [Q9UMR2-3]
UniGeneiHs.221761.

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
PDB entryMethodResolution (Å)ChainPositionsPDBsum
3EWSX-ray2.70A/B54-475[»]
3FHCX-ray2.80B68-302[»]
3FHTX-ray2.20A/B68-479[»]
3FMOX-ray2.51B1-300[»]
3FMPX-ray3.19B/D1-479[»]
3G0HX-ray2.70A54-475[»]
ProteinModelPortaliQ9UMR2.
SMRiQ9UMR2.
ModBaseiSearch...
MobiDBiSearch...

Protein-protein interaction databases

BioGridi116426. 110 interactors.
DIPiDIP-48486N.
IntActiQ9UMR2. 19 interactors.
MINTiMINT-4831823.
STRINGi9606.ENSP00000288071.

Protein family/group databases

TCDBi1.I.1.1.3. the nuclear pore complex (npc) family.

PTM databases

iPTMnetiQ9UMR2.
PhosphoSitePlusiQ9UMR2.

Polymorphism and mutation databases

BioMutaiDDX19B.
DMDMi10719979.

Proteomic databases

EPDiQ9UMR2.
PaxDbiQ9UMR2.
PeptideAtlasiQ9UMR2.
PRIDEiQ9UMR2.

Protocols and materials databases

DNASUi11269.
Structural Biology KnowledgebaseSearch...

Genome annotation databases

EnsembliENST00000288071; ENSP00000288071; ENSG00000157349. [Q9UMR2-1]
ENST00000355992; ENSP00000348271; ENSG00000157349. [Q9UMR2-2]
ENST00000393657; ENSP00000377267; ENSG00000157349. [Q9UMR2-3]
ENST00000451014; ENSP00000392639; ENSG00000157349. [Q9UMR2-4]
ENST00000563392; ENSP00000456574; ENSG00000157349. [Q9UMR2-3]
ENST00000568625; ENSP00000456757; ENSG00000157349. [Q9UMR2-3]
GeneIDi11269.
KEGGihsa:11269.
UCSCiuc002eyo.5. human. [Q9UMR2-1]

Organism-specific databases

CTDi11269.
GeneCardsiDDX19B.
HGNCiHGNC:2742. DDX19B.
HPAiCAB037229.
CAB037284.
HPA046380.
HPA066668.
MIMi605812. gene.
neXtProtiNX_Q9UMR2.
OpenTargetsiENSG00000157349.
PharmGKBiPA27208.
GenAtlasiSearch...

Phylogenomic databases

eggNOGiKOG0332. Eukaryota.
ENOG410XRGX. LUCA.
GeneTreeiENSGT00530000063236.
HOGENOMiHOG000268797.
HOVERGENiHBG107989.
InParanoidiQ9UMR2.
KOiK18655.
PhylomeDBiQ9UMR2.
TreeFamiTF314957.

Enzyme and pathway databases

BioCyciZFISH:ENSG00000157349-MONOMER.
BRENDAi3.6.4.13. 2681.

Miscellaneous databases

ChiTaRSiDDX19B. human.
EvolutionaryTraceiQ9UMR2.
GeneWikiiDDX19B.
GenomeRNAii11269.
PROiQ9UMR2.
SOURCEiSearch...

Gene expression databases

BgeeiENSG00000157349.
CleanExiHS_DDX19B.
ExpressionAtlasiQ9UMR2. baseline and differential.
GenevisibleiQ9UMR2. HS.

Family and domain databases

Gene3Di3.40.50.300. 2 hits.
InterProiIPR011545. DEAD/DEAH_box_helicase_dom.
IPR014001. Helicase_ATP-bd.
IPR001650. Helicase_C.
IPR027417. P-loop_NTPase.
IPR014014. RNA_helicase_DEAD_Q_motif.
[Graphical view]
PfamiPF00270. DEAD. 1 hit.
PF00271. Helicase_C. 1 hit.
[Graphical view]
SMARTiSM00487. DEXDc. 1 hit.
SM00490. HELICc. 1 hit.
[Graphical view]
SUPFAMiSSF52540. SSF52540. 1 hit.
PROSITEiPS51192. HELICASE_ATP_BIND_1. 1 hit.
PS51194. HELICASE_CTER. 1 hit.
PS51195. Q_MOTIF. 1 hit.
[Graphical view]
ProtoNetiSearch...

Entry informationi

Entry nameiDD19B_HUMAN
AccessioniPrimary (citable) accession number: Q9UMR2
Secondary accession number(s): B3KNE9
, B4DXS6, E7EMK4, Q6FIB7, Q6IAE0, Q96KE7, Q9H0U0
Entry historyi
Integrated into UniProtKB/Swiss-Prot: December 1, 2000
Last sequence update: May 1, 2000
Last modified: November 30, 2016
This is version 161 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 16
    Human chromosome 16: 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. MIM cross-references
    Online Mendelian Inheritance in Man (MIM) cross-references in UniProtKB/Swiss-Prot
  5. PDB cross-references
    Index of Protein Data Bank (PDB) cross-references
  6. 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.