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Protein

Streptavidin

Gene
N/A
Organism
Streptomyces avidinii
Status
Reviewed-Annotation score: Annotation score: 3 out of 5-Experimental evidence at protein leveli

Functioni

The biological function of streptavidin is not known. Forms a strong non-covalent specific complex with biotin (one molecule of biotin per subunit of streptavidin).

Sites

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Binding sitei67Biotin1
Binding sitei78Biotin1
Binding sitei116Biotin1
Binding sitei132Biotin1
Binding sitei144Biotin1

Keywords - Ligandi

Biotin

Enzyme and pathway databases

SABIO-RKP22629.

Names & Taxonomyi

Protein namesi
Recommended name:
Streptavidin
OrganismiStreptomyces avidinii
Taxonomic identifieri1895 [NCBI]
Taxonomic lineageiBacteriaActinobacteriaStreptomycetalesStreptomycetaceaeStreptomyces

Subcellular locationi

GO - Cellular componenti

Complete GO annotation...

Keywords - Cellular componenti

Secreted

Pathology & Biotechi

Chemistry databases

ChEMBLiCHEMBL1075026.

PTM / Processingi

Molecule processing

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Signal peptidei1 – 241 PublicationAdd BLAST24
ChainiPRO_000000272925 – 183StreptavidinAdd BLAST159

Proteomic databases

PRIDEiP22629.

Interactioni

Subunit structurei

Homotetramer.

Chemistry databases

BindingDBiP22629.

Structurei

Secondary structure

1183
Legend: HelixTurnBeta strandPDB Structure known for this area
Show more details
Feature keyPosition(s)DescriptionActionsGraphical viewLength
Turni39 – 41Combined sources3
Beta strandi43 – 47Combined sources5
Beta strandi48 – 50Combined sources3
Beta strandi52 – 57Combined sources6
Beta strandi61 – 68Combined sources8
Beta strandi70 – 73Combined sources4
Helixi74 – 76Combined sources3
Beta strandi78 – 84Combined sources7
Beta strandi90 – 92Combined sources3
Beta strandi95 – 104Combined sources10
Beta strandi109 – 121Combined sources13
Beta strandi123 – 125Combined sources3
Beta strandi127 – 136Combined sources10
Helixi140 – 145Combined sources6
Beta strandi147 – 156Combined sources10
Helixi161 – 169Combined sources9
Beta strandi172 – 176Combined sources5
Helixi178 – 180Combined sources3

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
PDB entryMethodResolution (Å)ChainPositionsPDBsum
1DF8X-ray1.51A/B37-163[»]
1HQQX-ray1.70A/B/C/D36-163[»]
1HXLX-ray1.80A/B36-163[»]
1HXZX-ray1.80A/B36-163[»]
1HY2X-ray2.00A/B/C/D36-163[»]
1I9HX-ray2.40A/B25-163[»]
1KFFX-ray1.90A/B/C/D38-163[»]
1KL3X-ray1.70A/B/C/D38-163[»]
1KL4X-ray1.70A/B/C/D38-163[»]
1KL5X-ray1.80A/B/C/D38-163[»]
1LCVX-ray2.30A/B39-159[»]
1LCWX-ray2.20A/B39-159[»]
1LCZX-ray1.95A/B25-159[»]
1LUQX-ray0.96A/B37-163[»]
1MEPX-ray1.65A/B/C/D37-163[»]
1MK5X-ray1.40A/B37-163[»]
1MM9X-ray1.66A37-163[»]
1MOYX-ray1.55A37-163[»]
1N43X-ray1.89A/B/C/D37-163[»]
1N4JX-ray2.18A37-163[»]
1N7YX-ray1.96A/B/C/D37-163[»]
1N9MX-ray1.60A/B/C/D37-163[»]
1N9YX-ray1.53A/B/C/D37-163[»]
1NBXX-ray1.70A/B/C/D37-163[»]
1NC9X-ray1.80A/B/C/D37-163[»]
1NDJX-ray1.81A/B/C/D37-163[»]
1NQMX-ray1.70A/B/C/D24-159[»]
1PTSX-ray2.00A/B37-157[»]
1RSTX-ray1.70B38-163[»]
1RSUX-ray1.70B38-163[»]
1RXHX-ray2.90A/B37-163[»]
1RXJX-ray1.14A/B/C/D39-159[»]
1RXKX-ray1.70A/B38-159[»]
1SLDX-ray2.50B25-159[»]
1SLEX-ray2.00B/D25-159[»]
1SLFX-ray1.76B/D25-159[»]
1SLGX-ray1.76B/D25-159[»]
1SREX-ray1.78A/B37-157[»]
1SRFX-ray2.00A/B37-157[»]
1SRGX-ray1.80A/B37-157[»]
1SRHX-ray2.20A/B37-157[»]
1SRIX-ray1.65A/B37-157[»]
1SRJX-ray1.80A/B37-157[»]
1STPX-ray2.60A25-183[»]
1STRX-ray1.80B/D37-159[»]
1STSX-ray1.95B/D37-159[»]
1SWAX-ray1.90A/B/C/D37-163[»]
1SWBX-ray1.85A/B/C/D37-163[»]
1SWCX-ray1.80A/B/C/D37-163[»]
1SWDX-ray1.90A/B/C/D37-163[»]
1SWEX-ray2.06A/B/C/D37-163[»]
1SWFX-ray2.00A/B/C/D75-163[»]
1SWGX-ray1.80A/B/C/D75-178[»]
1SWHX-ray1.70A/B/C/D37-163[»]
1SWJX-ray2.00A/B/C/D37-163[»]
1SWKX-ray2.00A/B/C/D37-163[»]
1SWLX-ray1.80A/B/C/D37-163[»]
1SWNX-ray2.20A/B/C/D37-163[»]
1SWOX-ray1.95A/B/C/D37-163[»]
1SWPX-ray2.00A/B/C/D37-163[»]
1SWQX-ray1.90A/B/C/D37-163[»]
1SWRX-ray1.90A/B/C/D37-163[»]
1SWSX-ray2.00A/B/C/D37-163[»]
1SWTX-ray2.00A/B37-163[»]
1SWUX-ray1.14A/B/C/D37-163[»]
1VWAX-ray1.85B/D37-159[»]
1VWBX-ray1.82B37-159[»]
1VWCX-ray1.86B37-159[»]
1VWDX-ray1.87B37-159[»]
1VWEX-ray1.50B37-159[»]
1VWFX-ray1.92B37-159[»]
1VWGX-ray1.46B37-159[»]
1VWHX-ray1.48B37-159[»]
1VWIX-ray1.50B/D37-159[»]
1VWJX-ray1.45B/D37-159[»]
1VWKX-ray1.45B/D37-159[»]
1VWLX-ray1.45B/D37-159[»]
1VWMX-ray1.60B37-159[»]
1VWNX-ray1.85B37-159[»]
1VWOX-ray1.65B37-159[»]
1VWPX-ray1.75B37-159[»]
1VWQX-ray1.70B37-159[»]
1VWRX-ray1.50B37-159[»]
2BC3X-ray1.54A/B38-183[»]
2F01X-ray0.85A/B37-163[»]
2G5LX-ray1.15A/B37-163[»]
2GH7X-ray1.00A/B37-163[»]
2IZAX-ray1.46A37-157[»]
2IZBX-ray1.20A37-158[»]
2IZCX-ray1.40B/D37-159[»]
2IZDX-ray1.60B/D37-159[»]
2IZEX-ray1.57B/D37-159[»]
2IZFX-ray1.58B/D37-159[»]
2IZGX-ray1.36B/D37-159[»]
2IZHX-ray1.36B/D37-159[»]
2IZIX-ray1.50A37-159[»]
2IZJX-ray1.30A37-159[»]
2IZKX-ray1.30A37-159[»]
2IZLX-ray1.48B/D37-159[»]
2QCBX-ray1.65A38-183[»]
2RTAX-ray1.39A25-159[»]
2RTBX-ray1.50B/D25-159[»]
2RTCX-ray1.50B/D25-159[»]
2RTDX-ray1.65B/D25-159[»]
2RTEX-ray1.50B/D25-159[»]
2RTFX-ray1.47B/D25-159[»]
2RTGX-ray1.39B/D25-159[»]
2RTHX-ray1.56B/D25-159[»]
2RTIX-ray1.40B/D25-159[»]
2RTJX-ray1.40A25-159[»]
2RTKX-ray1.82A25-159[»]
2RTLX-ray1.41A25-159[»]
2RTMX-ray1.30A25-159[»]
2RTNX-ray1.80B/D25-159[»]
2RTOX-ray1.58B/D25-159[»]
2RTPX-ray1.50B/D25-159[»]
2RTQX-ray1.39B/D25-159[»]
2RTRX-ray1.62B/D25-159[»]
2WPUX-ray1.92A38-183[»]
2Y3EX-ray1.45A/B37-163[»]
2Y3FX-ray1.49A37-163[»]
3MG5X-ray1.30A/B/C/D37-163[»]
3PK2X-ray1.90A38-183[»]
3RDMX-ray1.60A37-164[»]
3RDOX-ray1.40A37-164[»]
3RDQX-ray1.60A37-164[»]
3RDSX-ray1.50A37-164[»]
3RDUX-ray1.50A37-164[»]
3RDXX-ray2.10A/B37-164[»]
3RE5X-ray1.95A37-164[»]
3RE6X-ray1.82A37-164[»]
3RY1X-ray1.03A/B/C/D37-163[»]
3RY2X-ray0.95A/B37-163[»]
3T6FX-ray1.22A/B37-163[»]
3T6LX-ray1.30A37-163[»]
3WYPX-ray1.30A/B/C/D37-163[»]
3WYQX-ray1.00A/B37-163[»]
3WZNX-ray1.30A/B37-163[»]
3WZOX-ray1.50A/B/C/D37-163[»]
3WZPX-ray1.20A/B/C/D37-163[»]
3WZQX-ray1.70A/B/C/D37-163[»]
3X00X-ray1.30A/B/C/D37-163[»]
4BX5X-ray1.43A/C37-72[»]
B/D37-163[»]
4BX6X-ray1.60A/B/C/D37-163[»]
4BX7X-ray2.26A/B37-163[»]
4CPEX-ray1.06A/B37-163[»]
4CPFX-ray1.14A/B37-163[»]
4CPHX-ray1.64A/B/C/D37-163[»]
4CPIX-ray1.54A/B/C/D37-163[»]
4DNEX-ray1.88A/B1-183[»]
4EKVX-ray2.00A25-183[»]
4GD9X-ray1.50A/B/C/D37-163[»]
4GDAX-ray1.00A/B37-163[»]
4GJSX-ray1.85A/B38-183[»]
4GJVX-ray2.40A38-183[»]
4IRWX-ray1.40A36-163[»]
4JO6X-ray1.75A/B/C/D25-183[»]
4OKAX-ray2.50A38-183[»]
4Y59X-ray1.22A/B/C/D39-159[»]
4Y5DX-ray1.20A/B/C/D39-160[»]
4YVBX-ray1.35A/B/C/D40-159[»]
5CSEX-ray1.79A/B38-158[»]
5F2BX-ray1.70A38-183[»]
5K49X-ray1.72A38-183[»]
5K67X-ray1.70A38-183[»]
5K68X-ray1.40A38-183[»]
5L3YX-ray1.70A38-183[»]
ProteinModelPortaliP22629.
SMRiP22629.
ModBaseiSearch...
MobiDBiSearch...

Miscellaneous databases

EvolutionaryTraceiP22629.

Family & Domainsi

Domains and Repeats

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Domaini37 – 159Avidin-likePROSITE-ProRule annotationAdd BLAST123

Motif

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Motifi83 – 85Cell attachment site; atypical3

Sequence similaritiesi

Belongs to the avidin/streptavidin family.Curated
Contains 1 avidin-like domain.PROSITE-ProRule annotation

Keywords - Domaini

Signal

Family and domain databases

Gene3Di2.40.128.30. 1 hit.
InterProiIPR005469. Avidin.
IPR017889. Avidin-like_CS.
IPR005468. Avidin/str.
[Graphical view]
PfamiPF01382. Avidin. 1 hit.
[Graphical view]
PRINTSiPR00709. AVIDIN.
SUPFAMiSSF50876. SSF50876. 1 hit.
PROSITEiPS00577. AVIDIN_1. 1 hit.
PS51326. AVIDIN_2. 1 hit.
[Graphical view]

Sequencei

Sequence statusi: Complete.

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

P22629-1 [UniParc]FASTAAdd to basket

« Hide

        10         20         30         40         50
MRKIVVAAIA VSLTTVSITA SASADPSKDS KAQVSAAEAG ITGTWYNQLG
60 70 80 90 100
STFIVTAGAD GALTGTYESA VGNAESRYVL TGRYDSAPAT DGSGTALGWT
110 120 130 140 150
VAWKNNYRNA HSATTWSGQY VGGAEARINT QWLLTSGTTE ANAWKSTLVG
160 170 180
HDTFTKVKPS AASIDAAKKA GVNNGNPLDA VQQ
Length:183
Mass (Da):18,834
Last modified:August 1, 1991 - v1
Checksum:i4652D8AE018468F5
GO

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
X03591 Genomic DNA. Translation: CAA27265.1.
PIRiA23513.

Cross-referencesi

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
X03591 Genomic DNA. Translation: CAA27265.1.
PIRiA23513.

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
PDB entryMethodResolution (Å)ChainPositionsPDBsum
1DF8X-ray1.51A/B37-163[»]
1HQQX-ray1.70A/B/C/D36-163[»]
1HXLX-ray1.80A/B36-163[»]
1HXZX-ray1.80A/B36-163[»]
1HY2X-ray2.00A/B/C/D36-163[»]
1I9HX-ray2.40A/B25-163[»]
1KFFX-ray1.90A/B/C/D38-163[»]
1KL3X-ray1.70A/B/C/D38-163[»]
1KL4X-ray1.70A/B/C/D38-163[»]
1KL5X-ray1.80A/B/C/D38-163[»]
1LCVX-ray2.30A/B39-159[»]
1LCWX-ray2.20A/B39-159[»]
1LCZX-ray1.95A/B25-159[»]
1LUQX-ray0.96A/B37-163[»]
1MEPX-ray1.65A/B/C/D37-163[»]
1MK5X-ray1.40A/B37-163[»]
1MM9X-ray1.66A37-163[»]
1MOYX-ray1.55A37-163[»]
1N43X-ray1.89A/B/C/D37-163[»]
1N4JX-ray2.18A37-163[»]
1N7YX-ray1.96A/B/C/D37-163[»]
1N9MX-ray1.60A/B/C/D37-163[»]
1N9YX-ray1.53A/B/C/D37-163[»]
1NBXX-ray1.70A/B/C/D37-163[»]
1NC9X-ray1.80A/B/C/D37-163[»]
1NDJX-ray1.81A/B/C/D37-163[»]
1NQMX-ray1.70A/B/C/D24-159[»]
1PTSX-ray2.00A/B37-157[»]
1RSTX-ray1.70B38-163[»]
1RSUX-ray1.70B38-163[»]
1RXHX-ray2.90A/B37-163[»]
1RXJX-ray1.14A/B/C/D39-159[»]
1RXKX-ray1.70A/B38-159[»]
1SLDX-ray2.50B25-159[»]
1SLEX-ray2.00B/D25-159[»]
1SLFX-ray1.76B/D25-159[»]
1SLGX-ray1.76B/D25-159[»]
1SREX-ray1.78A/B37-157[»]
1SRFX-ray2.00A/B37-157[»]
1SRGX-ray1.80A/B37-157[»]
1SRHX-ray2.20A/B37-157[»]
1SRIX-ray1.65A/B37-157[»]
1SRJX-ray1.80A/B37-157[»]
1STPX-ray2.60A25-183[»]
1STRX-ray1.80B/D37-159[»]
1STSX-ray1.95B/D37-159[»]
1SWAX-ray1.90A/B/C/D37-163[»]
1SWBX-ray1.85A/B/C/D37-163[»]
1SWCX-ray1.80A/B/C/D37-163[»]
1SWDX-ray1.90A/B/C/D37-163[»]
1SWEX-ray2.06A/B/C/D37-163[»]
1SWFX-ray2.00A/B/C/D75-163[»]
1SWGX-ray1.80A/B/C/D75-178[»]
1SWHX-ray1.70A/B/C/D37-163[»]
1SWJX-ray2.00A/B/C/D37-163[»]
1SWKX-ray2.00A/B/C/D37-163[»]
1SWLX-ray1.80A/B/C/D37-163[»]
1SWNX-ray2.20A/B/C/D37-163[»]
1SWOX-ray1.95A/B/C/D37-163[»]
1SWPX-ray2.00A/B/C/D37-163[»]
1SWQX-ray1.90A/B/C/D37-163[»]
1SWRX-ray1.90A/B/C/D37-163[»]
1SWSX-ray2.00A/B/C/D37-163[»]
1SWTX-ray2.00A/B37-163[»]
1SWUX-ray1.14A/B/C/D37-163[»]
1VWAX-ray1.85B/D37-159[»]
1VWBX-ray1.82B37-159[»]
1VWCX-ray1.86B37-159[»]
1VWDX-ray1.87B37-159[»]
1VWEX-ray1.50B37-159[»]
1VWFX-ray1.92B37-159[»]
1VWGX-ray1.46B37-159[»]
1VWHX-ray1.48B37-159[»]
1VWIX-ray1.50B/D37-159[»]
1VWJX-ray1.45B/D37-159[»]
1VWKX-ray1.45B/D37-159[»]
1VWLX-ray1.45B/D37-159[»]
1VWMX-ray1.60B37-159[»]
1VWNX-ray1.85B37-159[»]
1VWOX-ray1.65B37-159[»]
1VWPX-ray1.75B37-159[»]
1VWQX-ray1.70B37-159[»]
1VWRX-ray1.50B37-159[»]
2BC3X-ray1.54A/B38-183[»]
2F01X-ray0.85A/B37-163[»]
2G5LX-ray1.15A/B37-163[»]
2GH7X-ray1.00A/B37-163[»]
2IZAX-ray1.46A37-157[»]
2IZBX-ray1.20A37-158[»]
2IZCX-ray1.40B/D37-159[»]
2IZDX-ray1.60B/D37-159[»]
2IZEX-ray1.57B/D37-159[»]
2IZFX-ray1.58B/D37-159[»]
2IZGX-ray1.36B/D37-159[»]
2IZHX-ray1.36B/D37-159[»]
2IZIX-ray1.50A37-159[»]
2IZJX-ray1.30A37-159[»]
2IZKX-ray1.30A37-159[»]
2IZLX-ray1.48B/D37-159[»]
2QCBX-ray1.65A38-183[»]
2RTAX-ray1.39A25-159[»]
2RTBX-ray1.50B/D25-159[»]
2RTCX-ray1.50B/D25-159[»]
2RTDX-ray1.65B/D25-159[»]
2RTEX-ray1.50B/D25-159[»]
2RTFX-ray1.47B/D25-159[»]
2RTGX-ray1.39B/D25-159[»]
2RTHX-ray1.56B/D25-159[»]
2RTIX-ray1.40B/D25-159[»]
2RTJX-ray1.40A25-159[»]
2RTKX-ray1.82A25-159[»]
2RTLX-ray1.41A25-159[»]
2RTMX-ray1.30A25-159[»]
2RTNX-ray1.80B/D25-159[»]
2RTOX-ray1.58B/D25-159[»]
2RTPX-ray1.50B/D25-159[»]
2RTQX-ray1.39B/D25-159[»]
2RTRX-ray1.62B/D25-159[»]
2WPUX-ray1.92A38-183[»]
2Y3EX-ray1.45A/B37-163[»]
2Y3FX-ray1.49A37-163[»]
3MG5X-ray1.30A/B/C/D37-163[»]
3PK2X-ray1.90A38-183[»]
3RDMX-ray1.60A37-164[»]
3RDOX-ray1.40A37-164[»]
3RDQX-ray1.60A37-164[»]
3RDSX-ray1.50A37-164[»]
3RDUX-ray1.50A37-164[»]
3RDXX-ray2.10A/B37-164[»]
3RE5X-ray1.95A37-164[»]
3RE6X-ray1.82A37-164[»]
3RY1X-ray1.03A/B/C/D37-163[»]
3RY2X-ray0.95A/B37-163[»]
3T6FX-ray1.22A/B37-163[»]
3T6LX-ray1.30A37-163[»]
3WYPX-ray1.30A/B/C/D37-163[»]
3WYQX-ray1.00A/B37-163[»]
3WZNX-ray1.30A/B37-163[»]
3WZOX-ray1.50A/B/C/D37-163[»]
3WZPX-ray1.20A/B/C/D37-163[»]
3WZQX-ray1.70A/B/C/D37-163[»]
3X00X-ray1.30A/B/C/D37-163[»]
4BX5X-ray1.43A/C37-72[»]
B/D37-163[»]
4BX6X-ray1.60A/B/C/D37-163[»]
4BX7X-ray2.26A/B37-163[»]
4CPEX-ray1.06A/B37-163[»]
4CPFX-ray1.14A/B37-163[»]
4CPHX-ray1.64A/B/C/D37-163[»]
4CPIX-ray1.54A/B/C/D37-163[»]
4DNEX-ray1.88A/B1-183[»]
4EKVX-ray2.00A25-183[»]
4GD9X-ray1.50A/B/C/D37-163[»]
4GDAX-ray1.00A/B37-163[»]
4GJSX-ray1.85A/B38-183[»]
4GJVX-ray2.40A38-183[»]
4IRWX-ray1.40A36-163[»]
4JO6X-ray1.75A/B/C/D25-183[»]
4OKAX-ray2.50A38-183[»]
4Y59X-ray1.22A/B/C/D39-159[»]
4Y5DX-ray1.20A/B/C/D39-160[»]
4YVBX-ray1.35A/B/C/D40-159[»]
5CSEX-ray1.79A/B38-158[»]
5F2BX-ray1.70A38-183[»]
5K49X-ray1.72A38-183[»]
5K67X-ray1.70A38-183[»]
5K68X-ray1.40A38-183[»]
5L3YX-ray1.70A38-183[»]
ProteinModelPortaliP22629.
SMRiP22629.
ModBaseiSearch...
MobiDBiSearch...

Chemistry databases

BindingDBiP22629.
ChEMBLiCHEMBL1075026.

Proteomic databases

PRIDEiP22629.

Protocols and materials databases

Structural Biology KnowledgebaseSearch...

Enzyme and pathway databases

SABIO-RKP22629.

Miscellaneous databases

EvolutionaryTraceiP22629.

Family and domain databases

Gene3Di2.40.128.30. 1 hit.
InterProiIPR005469. Avidin.
IPR017889. Avidin-like_CS.
IPR005468. Avidin/str.
[Graphical view]
PfamiPF01382. Avidin. 1 hit.
[Graphical view]
PRINTSiPR00709. AVIDIN.
SUPFAMiSSF50876. SSF50876. 1 hit.
PROSITEiPS00577. AVIDIN_1. 1 hit.
PS51326. AVIDIN_2. 1 hit.
[Graphical view]
ProtoNetiSearch...

Entry informationi

Entry nameiSAV_STRAV
AccessioniPrimary (citable) accession number: P22629
Entry historyi
Integrated into UniProtKB/Swiss-Prot: August 1, 1991
Last sequence update: August 1, 1991
Last modified: November 2, 2016
This is version 120 of the entry and version 1 of the sequence. [Complete history]
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programProkaryotic Protein Annotation Program

Miscellaneousi

Keywords - Technical termi

3D-structure, Direct protein sequencing

Documents

  1. PDB cross-references
    Index of Protein Data Bank (PDB) cross-references
  2. 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.