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Protein

L-2-hydroxyglutarate dehydrogenase, mitochondrial

Gene

L2HGDH

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

Functioni

Catalytic activityi

(S)-2-hydroxyglutarate + acceptor = 2-oxoglutarate + reduced acceptor.1 Publication

Cofactori

FAD1 Publication

Kineticsi

  1. KM=800 µM for L-2-hydroxyglutarate1 Publication

    GO - Molecular functioni

    • 2-hydroxyglutarate dehydrogenase activity Source: HGNC

    GO - Biological processi

    Complete GO annotation...

    Keywords - Molecular functioni

    Oxidoreductase

    Keywords - Ligandi

    FAD, Flavoprotein

    Enzyme and pathway databases

    BRENDAi1.1.99.2. 2681.
    ReactomeiREACT_25367. Interconversion of 2-oxoglutarate and 2-hydroxyglutarate.

    Names & Taxonomyi

    Protein namesi
    Recommended name:
    L-2-hydroxyglutarate dehydrogenase, mitochondrial (EC:1.1.99.2)
    Alternative name(s):
    Duranin
    Gene namesi
    Name:L2HGDH
    Synonyms:C14orf160
    OrganismiHomo sapiens (Human)
    Taxonomic identifieri9606 [NCBI]
    Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaEuarchontogliresPrimatesHaplorrhiniCatarrhiniHominidaeHomo
    ProteomesiUP000005640 Componenti: Chromosome 14

    Organism-specific databases

    HGNCiHGNC:20499. L2HGDH.

    Subcellular locationi

    GO - Cellular componenti

    • integral component of membrane Source: HGNC
    • integral component of mitochondrial inner membrane Source: HGNC
    • mitochondrial inner membrane Source: Reactome
    • mitochondrion Source: HGNC
    Complete GO annotation...

    Keywords - Cellular componenti

    Mitochondrion

    Pathology & Biotechi

    Involvement in diseasei

    L-2-hydroxyglutaric aciduria (L2HGA)3 Publications

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

    Disease descriptionA rare autosomal recessive disorder clinically characterized by mild psychomotor delay in the first years of life, followed by progressive cerebellar ataxia, dysarthria and moderate to severe mental retardation. Diagnosis is based on the presence of an excess of L-2-hydroxyglutaric acid in urine, blood and cerebrospinal fluid.

    See also OMIM:236792
    Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
    Natural varianti55 – 551G → D in L2HGA. 1 Publication
    VAR_025682
    Natural varianti57 – 571G → R in L2HGA. 1 Publication
    VAR_025683
    Natural varianti81 – 811K → E in L2HGA; alters protein processing and abolishes catalytic activity. 1 Publication
    VAR_025684
    Natural varianti98 – 981H → R in L2HGA. 1 Publication
    VAR_025685
    Natural varianti98 – 981H → Y in L2HGA. 1 Publication
    VAR_025686
    Natural varianti176 – 1761E → D in L2HGA; alters protein processing and abolishes catalytic activity. 1 Publication
    VAR_025687
    Natural varianti302 – 3021P → L in L2HGA. 2 Publications
    VAR_025689
    Natural varianti434 – 4341H → P in L2HGA. 1 Publication
    VAR_025690

    Keywords - Diseasei

    Disease mutation

    Organism-specific databases

    MIMi236792. phenotype.
    Orphaneti79314. L-2-hydroxyglutaric aciduria.
    PharmGKBiPA134971279.

    Polymorphism and mutation databases

    BioMutaiL2HGDH.
    DMDMi317373422.

    PTM / Processingi

    Molecule processing

    Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
    Transit peptidei1 – 5151MitochondrionSequence AnalysisAdd
    BLAST
    Chaini52 – 463412L-2-hydroxyglutarate dehydrogenase, mitochondrialPRO_0000228129Add
    BLAST

    Amino acid modifications

    Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
    Modified residuei104 – 1041N6-acetyllysine1 Publication
    Modified residuei155 – 1551N6-acetyllysine1 Publication
    Modified residuei173 – 1731N6-acetyllysineBy similarity

    Keywords - PTMi

    Acetylation

    Proteomic databases

    MaxQBiQ9H9P8.
    PaxDbiQ9H9P8.
    PRIDEiQ9H9P8.

    PTM databases

    PhosphoSiteiQ9H9P8.

    Expressioni

    Tissue specificityi

    Widely expressed. Highly expressed in brain, testis and muscle. Expressed to a lower extent in lymphocytes, fibroblasts, keratinocytes, placenta, bladder, small intestine, liver and bone marrow.1 Publication

    Gene expression databases

    BgeeiQ9H9P8.
    CleanExiHS_L2HGDH.
    ExpressionAtlasiQ9H9P8. baseline and differential.
    GenevisibleiQ9H9P8. HS.

    Interactioni

    Protein-protein interaction databases

    BioGridi123016. 7 interactions.
    STRINGi9606.ENSP00000267436.

    Structurei

    3D structure databases

    ProteinModelPortaliQ9H9P8.
    SMRiQ9H9P8. Positions 47-328.
    ModBaseiSearch...
    MobiDBiSearch...

    Family & Domainsi

    Sequence similaritiesi

    Belongs to the L2HGDH family.Curated

    Keywords - Domaini

    Transit peptide

    Phylogenomic databases

    eggNOGiCOG0579.
    GeneTreeiENSGT00490000043421.
    HOGENOMiHOG000245180.
    HOVERGENiHBG081883.
    InParanoidiQ9H9P8.
    KOiK00109.
    OMAiHFTRMID.
    PhylomeDBiQ9H9P8.
    TreeFamiTF105922.

    Family and domain databases

    InterProiIPR006076. FAD-dep_OxRdtase.
    [Graphical view]
    PfamiPF01266. DAO. 1 hit.
    [Graphical view]

    Sequences (2)i

    Sequence statusi: Complete.

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

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

    Isoform 1 (identifier: Q9H9P8-1) [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
    MVPALRYLVG ACGRARGLFA GGSPGACGFA SGRPRPLCGG SRSASTSSFD
    60 70 80 90 100
    IVIVGGGIVG LASARALILR HPSLSIGVLE KEKDLAVHQT GHNSGVIHSG
    110 120 130 140 150
    IYYKPESLKA KLCVQGAALL YEYCQQKGIS YKQCGKLIVA VEQEEIPRLQ
    160 170 180 190 200
    ALYEKGLQNG VPGLRLIQQE DIKKKEPYCR GLMAIDCPHT GIVDYRQVAL
    210 220 230 240 250
    SFAQDFQEAG GSVLTNFEVK GIEMAKESPS RSIDGMQYPI VIKNTKGEEI
    260 270 280 290 300
    RCQYVVTCAG LYSDRISELS GCTPDPRIVP FRGDYLLLKP EKCYLVKGNI
    310 320 330 340 350
    YPVPDSRFPF LGVHFTPRMD GSIWLGPNAV LAFKREGYRP FDFSATDVMD
    360 370 380 390 400
    IIINSGLIKL ASQNFSYGVT EMYKACFLGA TVKYLQKFIP EITISDILRG
    410 420 430 440 450
    PAGVRAQALD RDGNLVEDFV FDAGVGDIGN RILHVRNAPS PAATSSIAIS
    460
    GMIADEVQQR FEL
    Length:463
    Mass (Da):50,316
    Last modified:January 11, 2011 - v3
    Checksum:i1B6BC0C88543B7FF
    GO
    Isoform 2 (identifier: Q9H9P8-2) [UniParc]FASTAAdd to basket

    The sequence of this isoform differs from the canonical sequence as follows:
         400-400: G → QVAVRGPSWLWQQPMKVSDNNIYCFLWRCFALLLTGSTCSFK
         401-463: Missing.

    Note: No experimental confirmation available.
    Show »
    Length:441
    Mass (Da):48,505
    Checksum:i03F7B75151FFF85F
    GO

    Natural variant

    Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
    Natural varianti18 – 181L → R.2 Publications
    Corresponds to variant rs2275591 [ dbSNP | Ensembl ].
    VAR_025681
    Natural varianti33 – 331R → S.
    Corresponds to variant rs35710558 [ dbSNP | Ensembl ].
    VAR_057808
    Natural varianti55 – 551G → D in L2HGA. 1 Publication
    VAR_025682
    Natural varianti57 – 571G → R in L2HGA. 1 Publication
    VAR_025683
    Natural varianti81 – 811K → E in L2HGA; alters protein processing and abolishes catalytic activity. 1 Publication
    VAR_025684
    Natural varianti98 – 981H → R in L2HGA. 1 Publication
    VAR_025685
    Natural varianti98 – 981H → Y in L2HGA. 1 Publication
    VAR_025686
    Natural varianti176 – 1761E → D in L2HGA; alters protein processing and abolishes catalytic activity. 1 Publication
    VAR_025687
    Natural varianti178 – 1781Y → F.1 Publication
    VAR_025688
    Natural varianti302 – 3021P → L in L2HGA. 2 Publications
    VAR_025689
    Natural varianti434 – 4341H → P in L2HGA. 1 Publication
    VAR_025690

    Alternative sequence

    Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
    Alternative sequencei400 – 4001G → QVAVRGPSWLWQQPMKVSDN NIYCFLWRCFALLLTGSTCS FK in isoform 2. 1 PublicationVSP_017662
    Alternative sequencei401 – 46363Missing in isoform 2. 1 PublicationVSP_017663Add
    BLAST

    Sequence databases

    Select the link destinations:
    EMBLi
    GenBanki
    DDBJi
    Links Updated
    AY757363 mRNA. Translation: AAV52330.1.
    AK022680 mRNA. Translation: BAB14174.1.
    AL109758 Genomic DNA. No translation available.
    AL359397 Genomic DNA. No translation available.
    BC006117 mRNA. Translation: AAH06117.1.
    CCDSiCCDS9698.1. [Q9H9P8-1]
    RefSeqiNP_079160.1. NM_024884.2. [Q9H9P8-1]
    XP_005268132.1. XM_005268075.3. [Q9H9P8-1]
    UniGeneiHs.256034.

    Genome annotation databases

    EnsembliENST00000267436; ENSP00000267436; ENSG00000087299. [Q9H9P8-1]
    ENST00000421284; ENSP00000405559; ENSG00000087299. [Q9H9P8-1]
    GeneIDi79944.
    KEGGihsa:79944.
    UCSCiuc001wxu.3. human. [Q9H9P8-1]

    Keywords - Coding sequence diversityi

    Alternative splicing, Polymorphism

    Cross-referencesi

    Sequence databases

    Select the link destinations:
    EMBLi
    GenBanki
    DDBJi
    Links Updated
    AY757363 mRNA. Translation: AAV52330.1.
    AK022680 mRNA. Translation: BAB14174.1.
    AL109758 Genomic DNA. No translation available.
    AL359397 Genomic DNA. No translation available.
    BC006117 mRNA. Translation: AAH06117.1.
    CCDSiCCDS9698.1. [Q9H9P8-1]
    RefSeqiNP_079160.1. NM_024884.2. [Q9H9P8-1]
    XP_005268132.1. XM_005268075.3. [Q9H9P8-1]
    UniGeneiHs.256034.

    3D structure databases

    ProteinModelPortaliQ9H9P8.
    SMRiQ9H9P8. Positions 47-328.
    ModBaseiSearch...
    MobiDBiSearch...

    Protein-protein interaction databases

    BioGridi123016. 7 interactions.
    STRINGi9606.ENSP00000267436.

    PTM databases

    PhosphoSiteiQ9H9P8.

    Polymorphism and mutation databases

    BioMutaiL2HGDH.
    DMDMi317373422.

    Proteomic databases

    MaxQBiQ9H9P8.
    PaxDbiQ9H9P8.
    PRIDEiQ9H9P8.

    Protocols and materials databases

    DNASUi79944.
    Structural Biology KnowledgebaseSearch...

    Genome annotation databases

    EnsembliENST00000267436; ENSP00000267436; ENSG00000087299. [Q9H9P8-1]
    ENST00000421284; ENSP00000405559; ENSG00000087299. [Q9H9P8-1]
    GeneIDi79944.
    KEGGihsa:79944.
    UCSCiuc001wxu.3. human. [Q9H9P8-1]

    Organism-specific databases

    CTDi79944.
    GeneCardsiGC14M050704.
    H-InvDBHIX0011640.
    HGNCiHGNC:20499. L2HGDH.
    MIMi236792. phenotype.
    609584. gene.
    neXtProtiNX_Q9H9P8.
    Orphaneti79314. L-2-hydroxyglutaric aciduria.
    PharmGKBiPA134971279.
    GenAtlasiSearch...

    Phylogenomic databases

    eggNOGiCOG0579.
    GeneTreeiENSGT00490000043421.
    HOGENOMiHOG000245180.
    HOVERGENiHBG081883.
    InParanoidiQ9H9P8.
    KOiK00109.
    OMAiHFTRMID.
    PhylomeDBiQ9H9P8.
    TreeFamiTF105922.

    Enzyme and pathway databases

    BRENDAi1.1.99.2. 2681.
    ReactomeiREACT_25367. Interconversion of 2-oxoglutarate and 2-hydroxyglutarate.

    Miscellaneous databases

    ChiTaRSiL2HGDH. human.
    GeneWikiiL2HGDH.
    GenomeRNAii79944.
    NextBioi69898.
    PROiQ9H9P8.
    SOURCEiSearch...

    Gene expression databases

    BgeeiQ9H9P8.
    CleanExiHS_L2HGDH.
    ExpressionAtlasiQ9H9P8. baseline and differential.
    GenevisibleiQ9H9P8. HS.

    Family and domain databases

    InterProiIPR006076. FAD-dep_OxRdtase.
    [Graphical view]
    PfamiPF01266. DAO. 1 hit.
    [Graphical view]
    ProtoNetiSearch...

    Publicationsi

    « Hide 'large scale' publications
    1. "A gene encoding a putative FAD-dependent L-2-hydroxyglutarate dehydrogenase is mutated in L-2-hydroxyglutaric aciduria."
      Rzem R., Veiga-da-Cunha M., Noel G., Goffette S., Nassogne M.-C., Tabarki B., Schoeller C., Marquardt T., Vikkula M., van Schaftingen E.
      Proc. Natl. Acad. Sci. U.S.A. 101:16849-16854(2004) [PubMed] [Europe PMC] [Abstract]
      Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ISOFORM 1), VARIANTS L2HGA GLU-81 AND ASP-176, CHARACTERIZATION OF VARIANTS L2HGA GLU-81 AND ASP-176.
    2. "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(2004) [PubMed] [Europe PMC] [Abstract]
      Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA] (ISOFORM 1).
    3. "The DNA sequence and analysis of human chromosome 14."
      Heilig R., Eckenberg R., Petit J.-L., Fonknechten N., Da Silva C., Cattolico L., Levy M., Barbe V., De Berardinis V., Ureta-Vidal A., Pelletier E., Vico V., Anthouard V., Rowen L., Madan A., Qin S., Sun H., Du H.
      , Pepin K., Artiguenave F., Robert C., Cruaud C., Bruels T., Jaillon O., Friedlander L., Samson G., Brottier P., Cure S., Segurens B., Aniere F., Samain S., Crespeau H., Abbasi N., Aiach N., Boscus D., Dickhoff R., Dors M., Dubois I., Friedman C., Gouyvenoux M., James R., Madan A., Mairey-Estrada B., Mangenot S., Martins N., Menard M., Oztas S., Ratcliffe A., Shaffer T., Trask B., Vacherie B., Bellemere C., Belser C., Besnard-Gonnet M., Bartol-Mavel D., Boutard M., Briez-Silla S., Combette S., Dufosse-Laurent V., Ferron C., Lechaplais C., Louesse C., Muselet D., Magdelenat G., Pateau E., Petit E., Sirvain-Trukniewicz P., Trybou A., Vega-Czarny N., Bataille E., Bluet E., Bordelais I., Dubois M., Dumont C., Guerin T., Haffray S., Hammadi R., Muanga J., Pellouin V., Robert D., Wunderle E., Gauguet G., Roy A., Sainte-Marthe L., Verdier J., Verdier-Discala C., Hillier L.W., Fulton L., McPherson J., Matsuda F., Wilson R., Scarpelli C., Gyapay G., Wincker P., Saurin W., Quetier F., Waterston R., Hood L., Weissenbach J.
      Nature 421:601-607(2003) [PubMed] [Europe PMC] [Abstract]
      Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
    4. "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] (ISOFORM 2), VARIANT ARG-18.
      Tissue: Placenta.
    5. "The gene mutated in L-2-hydroxyglutaric aciduria encodes L-2-hydroxyglutarate dehydrogenase."
      Rzem R., Van Schaftingen E., Veiga-da-Cunha M.
      Biochimie 88:113-116(2006) [PubMed] [Europe PMC] [Abstract]
      Cited for: CATALYTIC ACTIVITY, BIOPHYSICOCHEMICAL PROPERTIES, SUBCELLULAR LOCATION, COFACTOR.
    6. "Lysine acetylation targets protein complexes and co-regulates major cellular functions."
      Choudhary C., Kumar C., Gnad F., Nielsen M.L., Rehman M., Walther T.C., Olsen J.V., Mann M.
      Science 325:834-840(2009) [PubMed] [Europe PMC] [Abstract]
      Cited for: ACETYLATION [LARGE SCALE ANALYSIS] AT LYS-104 AND LYS-155, IDENTIFICATION BY MASS SPECTROMETRY [LARGE SCALE ANALYSIS].
    7. Cited for: IDENTIFICATION BY MASS SPECTROMETRY [LARGE SCALE ANALYSIS].
    8. "An enzyme assisted RP-RPLC approach for in-depth analysis of human liver phosphoproteome."
      Bian Y., Song C., Cheng K., Dong M., Wang F., Huang J., Sun D., Wang L., Ye M., Zou H.
      J. Proteomics 96:253-262(2014) [PubMed] [Europe PMC] [Abstract]
      Cited for: IDENTIFICATION BY MASS SPECTROMETRY [LARGE SCALE ANALYSIS].
      Tissue: Liver.
    9. "L-2-hydroxyglutaric aciduria: identification of a mutant gene C14orf160, localized on chromosome 14q22.1."
      Topcu M., Jobard F., Halliez S., Coskun T., Yalcinkayal C., Gerceker F.O., Wanders R.J.A., Prud'homme J.-F., Lathrop M., Ozguc M., Fischer J.
      Hum. Mol. Genet. 13:2803-2811(2004) [PubMed] [Europe PMC] [Abstract]
      Cited for: VARIANTS L2HGA ASP-55; TYR-98 AND LEU-302, TISSUE SPECIFICITY.
    10. Cited for: VARIANTS L2HGA ARG-57; ARG-98; LEU-302 AND PRO-434, VARIANTS ARG-18 AND PHE-178.

    Entry informationi

    Entry nameiL2HDH_HUMAN
    AccessioniPrimary (citable) accession number: Q9H9P8
    Secondary accession number(s): Q9BRR1
    Entry historyi
    Integrated into UniProtKB/Swiss-Prot: March 21, 2006
    Last sequence update: January 11, 2011
    Last modified: June 24, 2015
    This is version 110 of the entry and version 3 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

    Was named 'duranin' in honor of Marinus Duran, who first described L-2-hydroxyglutaric aciduria.

    Keywords - Technical termi

    Complete proteome, Reference proteome

    Documents

    1. Human chromosome 14
      Human chromosome 14: 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.