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Protein

Alpha-amylase B

Gene

Amy-d

Organism
Drosophila melanogaster (Fruit fly)
Status
Reviewed-Annotation score: Annotation score: 5 out of 5-Protein inferred from homologyi

Functioni

Catalytic activityi

Endohydrolysis of (1->4)-alpha-D-glucosidic linkages in polysaccharides containing three or more (1->4)-alpha-linked D-glucose units.By similarity

Cofactori

Protein has several cofactor binding sites:
  • Ca2+By similarityNote: Binds 1 Ca2+ ion per subunit.By similarity
  • chlorideBy similarityNote: Binds 1 Cl- ion per subunit.By similarity

Sites

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Metal bindingi116 – 1161CalciumBy similarity
Metal bindingi165 – 1651Calcium; via carbonyl oxygenBy similarity
Metal bindingi174 – 1741CalciumBy similarity
Binding sitei202 – 2021ChlorideBy similarity
Active sitei204 – 2041NucleophileBy similarity
Metal bindingi208 – 2081Calcium; via carbonyl oxygenBy similarity
Active sitei241 – 2411Proton donorBy similarity
Binding sitei304 – 3041ChlorideBy similarity
Sitei306 – 3061Transition state stabilizerBy similarity
Binding sitei343 – 3431ChlorideBy similarity

GO - Molecular functioni

  • alpha-amylase activity Source: UniProtKB
  • calcium ion binding Source: UniProtKB

GO - Biological processi

  • carbohydrate metabolic process Source: UniProtKB
Complete GO annotation...

Keywords - Molecular functioni

Glycosidase, Hydrolase

Keywords - Biological processi

Carbohydrate metabolism

Keywords - Ligandi

Calcium, Chloride, Metal-binding

Enzyme and pathway databases

ReactomeiR-DME-189085. Digestion of dietary carbohydrate.

Protein family/group databases

CAZyiGH13. Glycoside Hydrolase Family 13.

Names & Taxonomyi

Protein namesi
Recommended name:
Alpha-amylase B (EC:3.2.1.1By similarity)
Alternative name(s):
1,4-alpha-D-glucan glucanohydrolase
Gene namesi
Name:Amy-d
Synonyms:AmyB
ORF Names:CG17876
OrganismiDrosophila melanogaster (Fruit fly)
Taxonomic identifieri7227 [NCBI]
Taxonomic lineageiEukaryotaMetazoaEcdysozoaArthropodaHexapodaInsectaPterygotaNeopteraEndopterygotaDipteraBrachyceraMuscomorphaEphydroideaDrosophilidaeDrosophilaSophophora
Proteomesi
  • UP000000803 Componenti: Chromosome 2R

Organism-specific databases

FlyBaseiFBgn0000078. Amy-d.

PTM / Processingi

Molecule processing

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Signal peptidei1 – 1818Add
BLAST
Chaini19 – 494476Alpha-amylase BPRO_0000001365Add
BLAST

Amino acid modifications

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Modified residuei19 – 191Pyrrolidone carboxylic acidBy similarity
Disulfide bondi46 ↔ 102By similarity
Disulfide bondi153 ↔ 167By similarity
Disulfide bondi376 ↔ 382By similarity
Disulfide bondi448 ↔ 460By similarity

Keywords - PTMi

Disulfide bond, Pyrrolidone carboxylic acid

Proteomic databases

PaxDbiP81641.

Expressioni

Gene expression databases

ExpressionAtlasiP81641. differential.
GenevisibleiP81641. DM.

Interactioni

Subunit structurei

Monomer.By similarity

Protein-protein interaction databases

BioGridi62629. 2 interactions.
MINTiMINT-757566.
STRINGi7227.FBpp0086155.

Structurei

3D structure databases

ProteinModelPortaliP81641.
SMRiP81641. Positions 21-494.
ModBaseiSearch...
MobiDBiSearch...

Family & Domainsi

Sequence similaritiesi

Belongs to the glycosyl hydrolase 13 family.Curated

Keywords - Domaini

Signal

Phylogenomic databases

eggNOGiKOG2212. Eukaryota.
COG0366. LUCA.
InParanoidiP81641.
KOiK01176.
OrthoDBiEOG7RJPR2.

Family and domain databases

Gene3Di2.60.40.1180. 1 hit.
3.20.20.80. 1 hit.
InterProiIPR006048. A-amylase/branching_C.
IPR031319. A-amylase_C.
IPR006046. Alpha_amylase.
IPR015902. Glyco_hydro_13.
IPR006047. Glyco_hydro_13_cat_dom.
IPR013780. Glyco_hydro_b.
IPR013781. Glyco_hydro_catalytic_dom.
IPR017853. Glycoside_hydrolase_SF.
[Graphical view]
PANTHERiPTHR10357. PTHR10357. 1 hit.
PfamiPF00128. Alpha-amylase. 1 hit.
PF02806. Alpha-amylase_C. 1 hit.
[Graphical view]
PRINTSiPR00110. ALPHAAMYLASE.
SMARTiSM00642. Aamy. 1 hit.
SM00632. Aamy_C. 1 hit.
[Graphical view]
SUPFAMiSSF51445. SSF51445. 1 hit.

Sequencei

Sequence statusi: Complete.

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

P81641-1 [UniParc]FASTAAdd to basket

« Hide

        10         20         30         40         50
MFLAKSIVCL ALLAVANAQF DTNYASGRSG MVHLFEWKWD DIAAECENFL
60 70 80 90 100
GPNGYAGVQV SPVNENAVKD SRPWWERYQP ISYKLETRSG NEEQFASMVK
110 120 130 140 150
RCNAVGVRTY VDVVFNHMAA DGGTYGTGGS TASPSSKSYP GVPYSSLDFN
160 170 180 190 200
PTCAISNYND ANEVRNCELV GLRDLNQGNS YVQDKVVEFL DHLIDLGVAG
210 220 230 240 250
FRVDAAKHMW PADLAVIYGR LKNLNTDHGF ASGSKAYIVQ EVIDMGGEAI
260 270 280 290 300
SKSEYTGLGA ITEFRHSDSI GKVFRGKDQL QYLTNWGTAW GFAASDRSLV
310 320 330 340 350
FVDNHDNQRG HGAGGADVLT YKVPKQYKMA SAFMLAHPFG TPRVMSSFSF
360 370 380 390 400
TDTDQGPPTT DGHNIASPIF NSDNSCSGGW VCEHRWRQIY NMVAFRNTVG
410 420 430 440 450
SDEIQNWWDN GSNQISFSRG SRGFVAFNND NYDLNSSLQT GLPAGTYCDV
460 470 480 490
ISGSKSGSSC TGKTVTVGSD GRASIYIGSS EDDGVLAIHV NAKL
Length:494
Mass (Da):53,795
Last modified:December 1, 2000 - v3
Checksum:iB477CB031754C298
GO

Polymorphismi

At least 6 electrophoretic isozymes are known: Amy1, Amy2, Amy3, Amy4, Amy5 and Amy6. Strains KO123 expresses Amy1; J87 expresses Amy3; 1420#1, L16 and TN256 express Amy6.1 Publication

Natural variant

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Natural varianti6 – 61Missing in strain: KN-22.
Natural varianti11 – 111A → S in strain: Berkeley, JP-5, JP-35, JP-55, JP-75, KN-12 and Oregon-R.
Natural varianti71 – 711S → R in strain: 1420#1, JP-169, JP-186, JP-190, KO123, KN-3, KN-9, KN-10, TN22 and TN256.
Natural varianti121 – 1211D → E in strain: JP-55.
Natural varianti121 – 1211D → G in strain: 1420#1, JP-190, JP-169, JP-186, KO123, TN22 and TN256.
Natural varianti121 – 1211D → N in strain: KN-10, KN-3 and KN-9.
Natural varianti138 – 1381S → T in strain: JP-75, KN-17, KN-21, KN-22 and L16.
Natural varianti156 – 1561S → R in strain: 1420#1, JP-169, JP-186, JP-190, KO123, KN-3, KN-9, KN-10, TN22 and TN256.
Natural varianti278 – 2781D → N in strain: 1420#1, AO168, J87, JP-60, JP-169, JP-186, JP-190, KO123, KN-3, KN-9, KN-10, TN22 and TN256.
Natural varianti288 – 2881T → I in strain: KN-15.
Natural varianti398 – 3981T → A in strain: Berkeley, JP-5, JP-35, JP-55, JP-60, JP-65, JP-70, JP-75, JP-169, JP-186, JP-190, KN-3, KN-9, KN-10, KN-12, KN-17, KN-21 and KN-23.
Natural varianti401 – 4011S → L in strain: Berkeley, JP-5, JP-35, JP-55, JP-65, JP-70, KN-12 and KN-21.
Natural varianti403 – 4031E → A in strain: 1420#1, AO168, J87, JP-60, JP-169, JP-186, JP-190, KO123, KN-3, KN-9, KN-10, TN22 and TN256.
Natural varianti410 – 4101N → S in strain: Berkeley, JP-5, JP-35, JP-55, JP-65 and KN-12.
Natural varianti465 – 4651V → I in strain: JP-1, JP-15, JP-84, KO140 and KN-27.
Natural varianti476 – 4761Y → N in strain: 1420#1, AO168, J87, JP-1, JP-15, JP-55, JP-60, JP-75, JP-84, JP-169, JP-186, JP-190, KO123, KO140, KN-3, KN-9, KN-10, KN-15, KN-17, KN-21, KN-22, KN-23, KN-27, L16, TN22 and TN256.
Natural varianti478 – 4781G → A in strain: KN-21.

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
X84405 Genomic DNA. Translation: CAA59126.1.
L22717 Genomic DNA. Translation: AAA92227.1.
L22718 Genomic DNA. Translation: AAA92228.1.
L22720 Genomic DNA. Translation: AAA92230.1.
L22724 Genomic DNA. Translation: AAA92232.1.
L22727 Genomic DNA. Translation: AAA92233.1.
L22728 Genomic DNA. Translation: AAA92242.1.
L22730 Genomic DNA. Translation: AAA92237.1.
L22732 Genomic DNA. Translation: AAA92243.1.
L22734 Genomic DNA. Translation: AAA92238.1.
AB043027 Genomic DNA. Translation: BAB32525.1.
AB043028 Genomic DNA. Translation: BAB32526.1.
AB043029 Genomic DNA. Translation: BAB32527.1.
AB043030 Genomic DNA. Translation: BAB32528.1.
AB043031 Genomic DNA. Translation: BAB32529.1.
AB043032 Genomic DNA. Translation: BAB32530.1.
AB043033 Genomic DNA. Translation: BAB32531.1.
AB043034 Genomic DNA. Translation: BAB32532.1.
AB043035 Genomic DNA. Translation: BAB32533.1.
AB043036 Genomic DNA. Translation: BAB32534.1.
AB043037 Genomic DNA. Translation: BAB32535.1.
AB043039 Genomic DNA. Translation: BAB32537.1.
AB043040 Genomic DNA. Translation: BAB32538.1.
AB043041 Genomic DNA. Translation: BAB32539.1.
AB043042 Genomic DNA. Translation: BAB32540.1.
AB043043 Genomic DNA. Translation: BAB32541.1.
AB043044 Genomic DNA. Translation: BAB32542.1.
AB043045 Genomic DNA. Translation: BAB32543.1.
AB043046 Genomic DNA. Translation: BAB32544.1.
AB043047 Genomic DNA. Translation: BAB32545.1.
AB043049 Genomic DNA. Translation: BAB72141.1.
AB043050 Genomic DNA. Translation: BAB72142.1.
AB043051 Genomic DNA. Translation: BAB72143.1.
AE013599 Genomic DNA. Translation: AAF57894.1.
X04570 Genomic DNA. Translation: CAA28239.1.
X84410 Genomic DNA. Translation: CAA59130.1.
PIRiS58951.
S58954.
S58959.
S58960.
S58962.
S58964.
RefSeqiNP_523768.1. NM_079044.2.
UniGeneiDm.18520.

Genome annotation databases

GeneIDi36932.
KEGGidme:Dmel_CG17876.

Keywords - Coding sequence diversityi

Polymorphism

Cross-referencesi

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
X84405 Genomic DNA. Translation: CAA59126.1.
L22717 Genomic DNA. Translation: AAA92227.1.
L22718 Genomic DNA. Translation: AAA92228.1.
L22720 Genomic DNA. Translation: AAA92230.1.
L22724 Genomic DNA. Translation: AAA92232.1.
L22727 Genomic DNA. Translation: AAA92233.1.
L22728 Genomic DNA. Translation: AAA92242.1.
L22730 Genomic DNA. Translation: AAA92237.1.
L22732 Genomic DNA. Translation: AAA92243.1.
L22734 Genomic DNA. Translation: AAA92238.1.
AB043027 Genomic DNA. Translation: BAB32525.1.
AB043028 Genomic DNA. Translation: BAB32526.1.
AB043029 Genomic DNA. Translation: BAB32527.1.
AB043030 Genomic DNA. Translation: BAB32528.1.
AB043031 Genomic DNA. Translation: BAB32529.1.
AB043032 Genomic DNA. Translation: BAB32530.1.
AB043033 Genomic DNA. Translation: BAB32531.1.
AB043034 Genomic DNA. Translation: BAB32532.1.
AB043035 Genomic DNA. Translation: BAB32533.1.
AB043036 Genomic DNA. Translation: BAB32534.1.
AB043037 Genomic DNA. Translation: BAB32535.1.
AB043039 Genomic DNA. Translation: BAB32537.1.
AB043040 Genomic DNA. Translation: BAB32538.1.
AB043041 Genomic DNA. Translation: BAB32539.1.
AB043042 Genomic DNA. Translation: BAB32540.1.
AB043043 Genomic DNA. Translation: BAB32541.1.
AB043044 Genomic DNA. Translation: BAB32542.1.
AB043045 Genomic DNA. Translation: BAB32543.1.
AB043046 Genomic DNA. Translation: BAB32544.1.
AB043047 Genomic DNA. Translation: BAB32545.1.
AB043049 Genomic DNA. Translation: BAB72141.1.
AB043050 Genomic DNA. Translation: BAB72142.1.
AB043051 Genomic DNA. Translation: BAB72143.1.
AE013599 Genomic DNA. Translation: AAF57894.1.
X04570 Genomic DNA. Translation: CAA28239.1.
X84410 Genomic DNA. Translation: CAA59130.1.
PIRiS58951.
S58954.
S58959.
S58960.
S58962.
S58964.
RefSeqiNP_523768.1. NM_079044.2.
UniGeneiDm.18520.

3D structure databases

ProteinModelPortaliP81641.
SMRiP81641. Positions 21-494.
ModBaseiSearch...
MobiDBiSearch...

Protein-protein interaction databases

BioGridi62629. 2 interactions.
MINTiMINT-757566.
STRINGi7227.FBpp0086155.

Protein family/group databases

CAZyiGH13. Glycoside Hydrolase Family 13.

Proteomic databases

PaxDbiP81641.

Protocols and materials databases

Structural Biology KnowledgebaseSearch...

Genome annotation databases

GeneIDi36932.
KEGGidme:Dmel_CG17876.

Organism-specific databases

CTDi36932.
FlyBaseiFBgn0000078. Amy-d.

Phylogenomic databases

eggNOGiKOG2212. Eukaryota.
COG0366. LUCA.
InParanoidiP81641.
KOiK01176.
OrthoDBiEOG7RJPR2.

Enzyme and pathway databases

ReactomeiR-DME-189085. Digestion of dietary carbohydrate.

Miscellaneous databases

GenomeRNAii36932.
PROiP81641.

Gene expression databases

ExpressionAtlasiP81641. differential.
GenevisibleiP81641. DM.

Family and domain databases

Gene3Di2.60.40.1180. 1 hit.
3.20.20.80. 1 hit.
InterProiIPR006048. A-amylase/branching_C.
IPR031319. A-amylase_C.
IPR006046. Alpha_amylase.
IPR015902. Glyco_hydro_13.
IPR006047. Glyco_hydro_13_cat_dom.
IPR013780. Glyco_hydro_b.
IPR013781. Glyco_hydro_catalytic_dom.
IPR017853. Glycoside_hydrolase_SF.
[Graphical view]
PANTHERiPTHR10357. PTHR10357. 1 hit.
PfamiPF00128. Alpha-amylase. 1 hit.
PF02806. Alpha-amylase_C. 1 hit.
[Graphical view]
PRINTSiPR00110. ALPHAAMYLASE.
SMARTiSM00642. Aamy. 1 hit.
SM00632. Aamy_C. 1 hit.
[Graphical view]
SUPFAMiSSF51445. SSF51445. 1 hit.
ProtoNetiSearch...

Publicationsi

« Hide 'large scale' publications
  1. "Nucleotide sequences of the duplicated Amylase structural genes in Drosophila melanogaster."
    Okuyama E., Yamazaki T.
    Proc. Jpn. Acad., B, Phys. Biol. Sci. 64:274-277(1988)
    Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA].
    Strain: TN329.
  2. "Evolutionary relationships and sequence variation of alpha-amylase variants encoded by duplicated genes in the Amy locus of Drosophila melanogaster."
    Inomata N., Shibata H., Okuyama E., Yamazaki T.
    Genetics 141:237-244(1995) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA], POLYMORPHISM.
    Strain: 1420#1, AO168, J87, KO123, KO140, L16, TN22, TN256 and TN329.
  3. "Molecular evolution of duplicated amylase gene regions in Drosophila melanogaster: evidence of positive selection in the coding regions and selective constraints in the cis-regulatory regions."
    Araki H., Inomata N., Yamazaki T.
    Genetics 157:667-677(2001) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA].
    Strain: JP-1, JP-15, JP-169, JP-186, JP-190, JP-35, JP-5, JP-55, JP-60, JP-65, JP-70, JP-75, JP-84, KN-10, KN-12, KN-15, KN-17, KN-21, KN-22, KN-23, KN-27, KN-3 and KN-9.
  4. "The genome sequence of Drosophila melanogaster."
    Adams M.D., Celniker S.E., Holt R.A., Evans C.A., Gocayne J.D., Amanatides P.G., Scherer S.E., Li P.W., Hoskins R.A., Galle R.F., George R.A., Lewis S.E., Richards S., Ashburner M., Henderson S.N., Sutton G.G., Wortman J.R., Yandell M.D.
    , Zhang Q., Chen L.X., Brandon R.C., Rogers Y.-H.C., Blazej R.G., Champe M., Pfeiffer B.D., Wan K.H., Doyle C., Baxter E.G., Helt G., Nelson C.R., Miklos G.L.G., Abril J.F., Agbayani A., An H.-J., Andrews-Pfannkoch C., Baldwin D., Ballew R.M., Basu A., Baxendale J., Bayraktaroglu L., Beasley E.M., Beeson K.Y., Benos P.V., Berman B.P., Bhandari D., Bolshakov S., Borkova D., Botchan M.R., Bouck J., Brokstein P., Brottier P., Burtis K.C., Busam D.A., Butler H., Cadieu E., Center A., Chandra I., Cherry J.M., Cawley S., Dahlke C., Davenport L.B., Davies P., de Pablos B., Delcher A., Deng Z., Mays A.D., Dew I., Dietz S.M., Dodson K., Doup L.E., Downes M., Dugan-Rocha S., Dunkov B.C., Dunn P., Durbin K.J., Evangelista C.C., Ferraz C., Ferriera S., Fleischmann W., Fosler C., Gabrielian A.E., Garg N.S., Gelbart W.M., Glasser K., Glodek A., Gong F., Gorrell J.H., Gu Z., Guan P., Harris M., Harris N.L., Harvey D.A., Heiman T.J., Hernandez J.R., Houck J., Hostin D., Houston K.A., Howland T.J., Wei M.-H., Ibegwam C., Jalali M., Kalush F., Karpen G.H., Ke Z., Kennison J.A., Ketchum K.A., Kimmel B.E., Kodira C.D., Kraft C.L., Kravitz S., Kulp D., Lai Z., Lasko P., Lei Y., Levitsky A.A., Li J.H., Li Z., Liang Y., Lin X., Liu X., Mattei B., McIntosh T.C., McLeod M.P., McPherson D., Merkulov G., Milshina N.V., Mobarry C., Morris J., Moshrefi A., Mount S.M., Moy M., Murphy B., Murphy L., Muzny D.M., Nelson D.L., Nelson D.R., Nelson K.A., Nixon K., Nusskern D.R., Pacleb J.M., Palazzolo M., Pittman G.S., Pan S., Pollard J., Puri V., Reese M.G., Reinert K., Remington K., Saunders R.D.C., Scheeler F., Shen H., Shue B.C., Siden-Kiamos I., Simpson M., Skupski M.P., Smith T.J., Spier E., Spradling A.C., Stapleton M., Strong R., Sun E., Svirskas R., Tector C., Turner R., Venter E., Wang A.H., Wang X., Wang Z.-Y., Wassarman D.A., Weinstock G.M., Weissenbach J., Williams S.M., Woodage T., Worley K.C., Wu D., Yang S., Yao Q.A., Ye J., Yeh R.-F., Zaveri J.S., Zhan M., Zhang G., Zhao Q., Zheng L., Zheng X.H., Zhong F.N., Zhong W., Zhou X., Zhu S.C., Zhu X., Smith H.O., Gibbs R.A., Myers E.W., Rubin G.M., Venter J.C.
    Science 287:2185-2195(2000) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
    Strain: Berkeley.
  5. Cited for: GENOME REANNOTATION.
    Strain: Berkeley.
  6. "The alpha-amylase gene in Drosophila melanogaster: nucleotide sequence, gene structure and expression motifs."
    Boer P.H., Hickey D.A.
    Nucleic Acids Res. 14:8399-8411(1986) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA] OF 1-22.
    Strain: Oregon-R.
  7. "Molecular analysis of cis-regulatory sequences at the alpha-amylase locus in Drosophila melanogaster."
    Hawley S.A., Doane W.W., Norman R.A.
    Biochem. Genet. 30:257-277(1992) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA] OF 1-13.
    Strain: Canton-S.

Entry informationi

Entry nameiAMYB_DROME
AccessioniPrimary (citable) accession number: P81641
Secondary accession number(s): Q27578
, Q27581, Q27585, Q27882, Q27885, Q27897, Q8WP56, Q95NK4, Q969D1, Q9BH39, Q9BH72, Q9BPS5, Q9BPS6, Q9BPS7, Q9BPS8, Q9BPT0, Q9BPT1, Q9BPT2, Q9BPT3, Q9V7Z0
Entry historyi
Integrated into UniProtKB/Swiss-Prot: December 1, 2000
Last sequence update: December 1, 2000
Last modified: June 8, 2016
This is version 131 of the entry and version 3 of the sequence. [Complete history]
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programDrosophila annotation project

Miscellaneousi

Keywords - Technical termi

Complete proteome, Reference proteome

Documents

  1. Drosophila
    Drosophila: entries, gene names and cross-references to FlyBase
  2. Glycosyl hydrolases
    Classification of glycosyl hydrolase families and list of entries
  3. 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.