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Protein

Membrane frizzled-related protein

Gene

MFRP

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

Functioni

May play a role in eye development.1 Publication

GO - Biological processi

  1. embryo development Source: UniProtKB
Complete GO annotation...

Names & Taxonomyi

Protein namesi
Recommended name:
Membrane frizzled-related protein
Alternative name(s):
Membrane-type frizzled-related protein
Gene namesi
Name:MFRP
OrganismiHomo sapiens (Human)
Taxonomic identifieri9606 [NCBI]
Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaEuarchontogliresPrimatesHaplorrhiniCatarrhiniHominidaeHomo
ProteomesiUP000005640 Componenti: Chromosome 11

Organism-specific databases

HGNCiHGNC:18121. MFRP.

Subcellular locationi

Topology

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Topological domaini1 – 6969CytoplasmicSequence AnalysisAdd
BLAST
Transmembranei70 – 9021Helical; Signal-anchor for type II membrane proteinSequence AnalysisAdd
BLAST
Topological domaini91 – 579489ExtracellularSequence AnalysisAdd
BLAST

GO - Cellular componenti

  1. apical plasma membrane Source: UniProtKB-SubCell
  2. integral component of membrane Source: UniProtKB
Complete GO annotation...

Keywords - Cellular componenti

Cell membrane, Membrane

Pathology & Biotechi

Involvement in diseasei

Nanophthalmos 2 (NNO2)1 Publication

The disease is caused by mutations affecting the gene represented in this entry.

Disease descriptionRare autosomal recessive disorder of eye development characterized by extreme hyperopia and small functional eyes.

See also OMIM:609549
Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Natural varianti182 – 1821I → T in NNO2. 1 Publication
VAR_025694
Microphthalmia, isolated, 5 (MCOP5)1 Publication

The disease is caused by mutations affecting the gene represented in this entry.

Disease descriptionA disorder characterized by posterior microphthalmia, retinitis pigmentosa, foveoschisis and optic disk drusen. Microphthalmia is a disorder of eye formation, ranging from small size of a single eye to complete bilateral absence of ocular tissues. Ocular abnormalities like opacities of the cornea and lens, scaring of the retina and choroid, and other abnormalities may also be present.

See also OMIM:611040

Keywords - Diseasei

Disease mutation, Microphthalmia, Retinitis pigmentosa

Organism-specific databases

MIMi609549. phenotype.
611040. phenotype.
Orphaneti251279. Microphthalmia - retinitis pigmentosa - foveoschisis - optic disc drusen.
35612. Nanophthalmia.
PharmGKBiPA30776.

PTM / Processingi

Molecule processing

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Chaini1 – 579579Membrane frizzled-related proteinPRO_0000228132Add
BLAST

Amino acid modifications

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Disulfide bondi144 ↔ 170By similarity
Disulfide bondi197 ↔ 216By similarity
Glycosylationi227 – 2271N-linked (GlcNAc...)Sequence Analysis
Disulfide bondi260 ↔ 272By similarity
Disulfide bondi267 ↔ 285By similarity
Disulfide bondi279 ↔ 294By similarity
Disulfide bondi301 ↔ 327By similarity
Disulfide bondi354 ↔ 377By similarity
Glycosylationi415 – 4151N-linked (GlcNAc...)Sequence Analysis
Disulfide bondi421 ↔ 433By similarity
Disulfide bondi428 ↔ 446By similarity
Disulfide bondi440 ↔ 454By similarity
Disulfide bondi466 ↔ 528By similarity
Disulfide bondi474 ↔ 521By similarity
Disulfide bondi512 ↔ 549By similarity
Disulfide bondi538 ↔ 576By similarity
Disulfide bondi542 ↔ 564By similarity

Keywords - PTMi

Disulfide bond, Glycoprotein

Proteomic databases

PaxDbiQ9BY79.
PRIDEiQ9BY79.

Expressioni

Tissue specificityi

Specifically expressed in brain. Strongly expressed in medulla oblongata and to a lower extent in hippocampus and corpus callosum. Expressed in keratinocytes.2 Publications

Developmental stagei

Expressed in fetal brain.1 Publication

Gene expression databases

CleanExiHS_MFRP.
GenevestigatoriQ9BY79.

Organism-specific databases

HPAiHPA042946.

Interactioni

Subunit structurei

Interacts with C1QTNF5.1 Publication

Protein-protein interaction databases

BioGridi123684. 1 interaction.
125392. 1 interaction.
STRINGi9606.ENSP00000391664.

Structurei

3D structure databases

ProteinModelPortaliQ9BY79.
SMRiQ9BY79. Positions 127-428, 463-572.
ModBaseiSearch...
MobiDBiSearch...

Family & Domainsi

Domains and Repeats

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Domaini144 – 253110CUB 1PROSITE-ProRule annotationAdd
BLAST
Domaini259 – 29537LDL-receptor class A 1PROSITE-ProRule annotationAdd
BLAST
Domaini301 – 414114CUB 2PROSITE-ProRule annotationAdd
BLAST
Domaini420 – 45536LDL-receptor class A 2PROSITE-ProRule annotationAdd
BLAST
Domaini461 – 579119FZPROSITE-ProRule annotationAdd
BLAST

Compositional bias

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Compositional biasi111 – 12111Poly-ThrAdd
BLAST

Sequence similaritiesi

Contains 2 CUB domains.PROSITE-ProRule annotation
Contains 1 FZ (frizzled) domain.PROSITE-ProRule annotation
Contains 2 LDL-receptor class A domains.PROSITE-ProRule annotation

Keywords - Domaini

Repeat, Signal-anchor, Transmembrane, Transmembrane helix

Phylogenomic databases

eggNOGiNOG261421.
GeneTreeiENSGT00760000119018.
HOGENOMiHOG000048709.
HOVERGENiHBG081968.
InParanoidiQ9BY79.
OMAiGLEACAQ.
OrthoDBiEOG7S4X5R.
PhylomeDBiQ9BY79.
TreeFamiTF316506.

Family and domain databases

Gene3Di1.10.2000.10. 1 hit.
2.60.120.290. 2 hits.
4.10.400.10. 2 hits.
InterProiIPR000859. CUB_dom.
IPR020067. Frizzled_dom.
IPR023415. LDLR_class-A_CS.
IPR002172. LDrepeatLR_classA_rpt.
[Graphical view]
PfamiPF00431. CUB. 2 hits.
PF01392. Fz. 1 hit.
PF00057. Ldl_recept_a. 1 hit.
[Graphical view]
PRINTSiPR00261. LDLRECEPTOR.
SMARTiSM00042. CUB. 2 hits.
SM00192. LDLa. 2 hits.
[Graphical view]
SUPFAMiSSF49854. SSF49854. 2 hits.
SSF57424. SSF57424. 2 hits.
SSF63501. SSF63501. 1 hit.
PROSITEiPS01180. CUB. 2 hits.
PS50038. FZ. 1 hit.
PS01209. LDLRA_1. 1 hit.
PS50068. LDLRA_2. 2 hits.
[Graphical view]

Sequences (2)i

Sequence statusi: Complete.

This entry describes 2 isoformsi produced by alternative splicing. AlignAdd to basket

Isoform 1 (identifier: Q9BY79-1) [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
MKDFSDVILC MEATESSKTE FCNPAFEPES GPPCPPPVFP EDASYSVPAP
60 70 80 90 100
WHGRRPRGLR PDCRFSWLCV LLLSSLLLLL LGLLVAIILA QLQAAPPSGA
110 120 130 140 150
SHSPLPAGGL TTTTTTPTIT TSQAAGTPKG QQESGVSPSP QSTCGGLLSG
160 170 180 190 200
PRGFFSSPNY PDPYPPNTHC VWHIQVATDH AIQLKIEALS IESVASCLFD
210 220 230 240 250
RLELSPEPEG PLLRVCGRVP PPTLNTNASH LLVVFVSDSS VEGFGFHAWY
260 270 280 290 300
QAMAPGRGSC AHDEFRCDQL ICLLPDSVCD GFANCADGSD ETNCSAKFSG
310 320 330 340 350
CGGNLTGLQG TFSTPSYLQQ YPHQLLCTWH ISVPAGHSIE LQFHNFSLEA
360 370 380 390 400
QDECKFDYVE VYETSSSGAF SLLGRFCGAE PPPHLVSSHH ELAVLFRTDH
410 420 430 440 450
GISSGGFSAT YLAFNATENP CGPSELSCQA GGCKGVQWMC DMWRDCTDGS
460 470 480 490 500
DDNCSGPLFP PPELACEPVQ VEMCLGLSYN TTAFPNIWVG MITQEEVVEV
510 520 530 540 550
LSGYKSLTSL PCYQHFRRLL CGLLVPRCTP LGSVLPPCRS VCQEAEHQCQ
560 570
SGLALLGTPW PFNCNRLPEA ADLEACAQP
Length:579
Mass (Da):62,212
Last modified:May 31, 2001 - v1
Checksum:i8E5F8D3A1C4BB074
GO
Isoform 2 (identifier: Q9BY79-2) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     301-387: CGGNLTGLQG...GAEPPPHLVS → SVEQSHPPTS...TAAAPCSHPQ
     388-505: Missing.

Note: No experimental confirmation available.

Show »
Length:461
Mass (Da):48,919
Checksum:i9165FD3A20A2A44C
GO

Experimental Info

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Sequence conflicti40 – 401P → Q in CAH93521 (PubMed:16123440).Curated
Sequence conflicti83 – 831Missing in CAH93521 (PubMed:16123440).Curated
Sequence conflicti393 – 3931A → S in BAB70859 (PubMed:14702039).Curated

Natural variant

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Natural varianti54 – 541R → G.1 Publication
Corresponds to variant rs139436396 [ dbSNP | Ensembl ].
VAR_025691
Natural varianti119 – 1191I → V.1 Publication
Corresponds to variant rs4639950 [ dbSNP | Ensembl ].
VAR_025692
Natural varianti136 – 1361V → M.2 Publications
Corresponds to variant rs3814762 [ dbSNP | Ensembl ].
VAR_025693
Natural varianti182 – 1821I → T in NNO2. 1 Publication
VAR_025694
Natural varianti259 – 2591S → D Requires 2 nucleotide substitutions. 1 Publication
VAR_071160
Natural varianti449 – 4491G → S.1 Publication
VAR_025695
Natural varianti514 – 5141Q → H.1 Publication
VAR_025696

Alternative sequence

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Alternative sequencei301 – 38787CGGNL…PHLVS → SVEQSHPPTSSPRTMSWLCC LGQIMASAVEASQPPTWPSM PRRTPVGPVSSPARQEGVRV CSGCVTCGETAPMAAMTTAA APCSHPQ in isoform 2. 1 PublicationVSP_055928Add
BLAST
Alternative sequencei388 – 505118Missing in isoform 2. 1 PublicationVSP_055929Add
BLAST

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
AB055505 mRNA. Translation: BAB39771.1.
AJ862823 mRNA. Translation: CAH93521.1.
AK055132 mRNA. Translation: BAB70859.1.
AK295203 mRNA. Translation: BAG58200.1.
EF444994 Genomic DNA. Translation: ACA06013.1.
EF444994 Genomic DNA. Translation: ACA06015.1.
AP003396 Genomic DNA. No translation available.
CH471065 Genomic DNA. Translation: EAW67483.1.
CCDSiCCDS8421.1. [Q9BY79-1]
PIRiJC7629.
RefSeqiNP_113621.1. NM_031433.3. [Q9BY79-1]
UniGeneiHs.632102.

Genome annotation databases

EnsembliENST00000360167; ENSP00000353291; ENSG00000235718. [Q9BY79-2]
ENST00000449574; ENSP00000391664; ENSG00000235718. [Q9BY79-1]
GeneIDi83552.
KEGGihsa:83552.
UCSCiuc001pwj.2. human. [Q9BY79-1]

Polymorphism databases

DMDMi74717666.

Keywords - Coding sequence diversityi

Alternative splicing, Polymorphism

Cross-referencesi

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
AB055505 mRNA. Translation: BAB39771.1.
AJ862823 mRNA. Translation: CAH93521.1.
AK055132 mRNA. Translation: BAB70859.1.
AK295203 mRNA. Translation: BAG58200.1.
EF444994 Genomic DNA. Translation: ACA06013.1.
EF444994 Genomic DNA. Translation: ACA06015.1.
AP003396 Genomic DNA. No translation available.
CH471065 Genomic DNA. Translation: EAW67483.1.
CCDSiCCDS8421.1. [Q9BY79-1]
PIRiJC7629.
RefSeqiNP_113621.1. NM_031433.3. [Q9BY79-1]
UniGeneiHs.632102.

3D structure databases

ProteinModelPortaliQ9BY79.
SMRiQ9BY79. Positions 127-428, 463-572.
ModBaseiSearch...
MobiDBiSearch...

Protein-protein interaction databases

BioGridi123684. 1 interaction.
125392. 1 interaction.
STRINGi9606.ENSP00000391664.

Polymorphism databases

DMDMi74717666.

Proteomic databases

PaxDbiQ9BY79.
PRIDEiQ9BY79.

Protocols and materials databases

DNASUi83552.
Structural Biology KnowledgebaseSearch...

Genome annotation databases

EnsembliENST00000360167; ENSP00000353291; ENSG00000235718. [Q9BY79-2]
ENST00000449574; ENSP00000391664; ENSG00000235718. [Q9BY79-1]
GeneIDi83552.
KEGGihsa:83552.
UCSCiuc001pwj.2. human. [Q9BY79-1]

Organism-specific databases

CTDi83552.
GeneCardsiGC11M119218.
HGNCiHGNC:18121. MFRP.
HPAiHPA042946.
MIMi606227. gene.
609549. phenotype.
611040. phenotype.
neXtProtiNX_Q9BY79.
Orphaneti251279. Microphthalmia - retinitis pigmentosa - foveoschisis - optic disc drusen.
35612. Nanophthalmia.
PharmGKBiPA30776.
GenAtlasiSearch...

Phylogenomic databases

eggNOGiNOG261421.
GeneTreeiENSGT00760000119018.
HOGENOMiHOG000048709.
HOVERGENiHBG081968.
InParanoidiQ9BY79.
OMAiGLEACAQ.
OrthoDBiEOG7S4X5R.
PhylomeDBiQ9BY79.
TreeFamiTF316506.

Miscellaneous databases

GenomeRNAii83552.
NextBioi35466294.
PROiQ9BY79.
SOURCEiSearch...

Gene expression databases

CleanExiHS_MFRP.
GenevestigatoriQ9BY79.

Family and domain databases

Gene3Di1.10.2000.10. 1 hit.
2.60.120.290. 2 hits.
4.10.400.10. 2 hits.
InterProiIPR000859. CUB_dom.
IPR020067. Frizzled_dom.
IPR023415. LDLR_class-A_CS.
IPR002172. LDrepeatLR_classA_rpt.
[Graphical view]
PfamiPF00431. CUB. 2 hits.
PF01392. Fz. 1 hit.
PF00057. Ldl_recept_a. 1 hit.
[Graphical view]
PRINTSiPR00261. LDLRECEPTOR.
SMARTiSM00042. CUB. 2 hits.
SM00192. LDLa. 2 hits.
[Graphical view]
SUPFAMiSSF49854. SSF49854. 2 hits.
SSF57424. SSF57424. 2 hits.
SSF63501. SSF63501. 1 hit.
PROSITEiPS01180. CUB. 2 hits.
PS50038. FZ. 1 hit.
PS01209. LDLRA_1. 1 hit.
PS50068. LDLRA_2. 2 hits.
[Graphical view]
ProtoNetiSearch...

Publicationsi

« Hide 'large scale' publications
  1. "Molecular cloning and characterization of MFRP, a novel gene encoding a membrane-type frizzled-related protein."
    Katoh M.
    Biochem. Biophys. Res. Commun. 282:116-123(2000) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ISOFORM 1), DEVELOPMENTAL STAGE, TISSUE SPECIFICITY.
    Tissue: Fetal brain.
  2. "Sequencing arrays for screening multiple genes associated with early-onset human retinal degenerations on a high-throughput platform."
    Mandal M.N.A., Heckenlively J.R., Burch T., Chen L., Vasireddy V., Koenekoop R.K., Sieving P.A., Ayyagari R.
    Invest. Ophthalmol. Vis. Sci. 46:3355-3362(2004) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ISOFORM 1), VARIANT MET-136.
  3. "Complete sequencing and characterization of 21,243 full-length human cDNAs."
    Ota T., Suzuki Y., Nishikawa T., Otsuki T., Sugiyama T., Irie R., Wakamatsu A., Hayashi K., Sato H., Nagai K., Kimura K., Makita H., Sekine M., Obayashi M., Nishi T., Shibahara T., Tanaka T., Ishii S.
    , Yamamoto J., Saito K., Kawai Y., Isono Y., Nakamura Y., Nagahari K., Murakami K., Yasuda T., Iwayanagi T., Wagatsuma M., Shiratori A., Sudo H., Hosoiri T., Kaku Y., Kodaira H., Kondo H., Sugawara M., Takahashi M., Kanda K., Yokoi T., Furuya T., Kikkawa E., Omura Y., Abe K., Kamihara K., Katsuta N., Sato K., Tanikawa M., Yamazaki M., Ninomiya K., Ishibashi T., Yamashita H., Murakawa K., Fujimori K., Tanai H., Kimata M., Watanabe M., Hiraoka S., Chiba Y., Ishida S., Ono Y., Takiguchi S., Watanabe S., Yosida M., Hotuta T., Kusano J., Kanehori K., Takahashi-Fujii A., Hara H., Tanase T.-O., Nomura Y., Togiya S., Komai F., Hara R., Takeuchi K., Arita M., Imose N., Musashino K., Yuuki H., Oshima A., Sasaki N., Aotsuka S., Yoshikawa Y., Matsunawa H., Ichihara T., Shiohata N., Sano S., Moriya S., Momiyama H., Satoh N., Takami S., Terashima Y., Suzuki O., Nakagawa S., Senoh A., Mizoguchi H., Goto Y., Shimizu F., Wakebe H., Hishigaki H., Watanabe T., Sugiyama A., Takemoto M., Kawakami B., Yamazaki M., Watanabe K., Kumagai A., Itakura S., Fukuzumi Y., Fujimori Y., Komiyama M., Tashiro H., Tanigami A., Fujiwara T., Ono T., Yamada K., Fujii Y., Ozaki K., Hirao M., Ohmori Y., Kawabata A., Hikiji T., Kobatake N., Inagaki H., Ikema Y., Okamoto S., Okitani R., Kawakami T., Noguchi S., Itoh T., Shigeta K., Senba T., Matsumura K., Nakajima Y., Mizuno T., Morinaga M., Sasaki M., Togashi T., Oyama M., Hata H., Watanabe M., Komatsu T., Mizushima-Sugano J., Satoh T., Shirai Y., Takahashi Y., Nakagawa K., Okumura K., Nagase T., Nomura N., Kikuchi H., Masuho Y., Yamashita R., Nakai K., Yada T., Nakamura Y., Ohara O., Isogai T., Sugano S.
    Nat. Genet. 36:40-45(2003) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA] (ISOFORMS 1 AND 2).
    Tissue: Brain and Caudate nucleus.
  4. NHLBI resequencing and genotyping service (RS&G)
    Submitted (JAN-2007) to the EMBL/GenBank/DDBJ databases
    Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA], VARIANT ASP-259.
  5. Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
  6. Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
  7. Cited for: INTERACTION WITH C1QTNF5.
  8. "Bone morphogenetic protein-2 modulates Wnt and frizzled expression and enhances the canonical pathway of Wnt signaling in normal keratinocytes."
    Yang L., Yamasaki K., Shirakata Y., Dai X., Tokumaru S., Yahata Y., Tohyama M., Hanakawa Y., Sayama K., Hashimoto K.
    J. Dermatol. Sci. 42:111-119(2005) [PubMed] [Europe PMC] [Abstract]
    Cited for: TISSUE SPECIFICITY.
  9. "Mutation screen of the membrane-type frizzled-related protein (MFRP) gene in patients with inherited retinal degenerations."
    Pauer G.J.T., Xi Q., Zhang K., Traboulsi E.I., Hagstrom S.A.
    Ophthalmic Genet. 26:157-161(2004) [PubMed] [Europe PMC] [Abstract]
    Cited for: VARIANTS GLY-54; VAL-119; MET-136; SER-449 AND HIS-514.
  10. Cited for: VARIANT NNO2 THR-182, FUNCTION.
  11. "A new autosomal recessive syndrome consisting of posterior microphthalmos, retinitis pigmentosa, foveoschisis, and optic disc drusen is caused by a MFRP gene mutation."
    Ayala-Ramirez R., Graue-Wiechers F., Robredo V., Amato-Almanza M., Horta-Diez I., Zenteno J.C.
    Mol. Vis. 12:1483-1489(2005) [PubMed] [Europe PMC] [Abstract]
    Cited for: INVOLVEMENT IN MCOP5.

Entry informationi

Entry nameiMFRP_HUMAN
AccessioniPrimary (citable) accession number: Q9BY79
Secondary accession number(s): B0YJ36
, B0YJ37, B4DHN8, Q335M3, Q96DQ9
Entry historyi
Integrated into UniProtKB/Swiss-Prot: March 20, 2006
Last sequence update: May 31, 2001
Last modified: March 3, 2015
This is version 110 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

Miscellaneous

This protein is produced by a bicistronic gene which also produces the C1QTNF5 protein from a non-overlapping reading frame.

Keywords - Technical termi

Complete proteome, Reference proteome

Documents

  1. Human chromosome 11
    Human chromosome 11: 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. 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.