ID   UBIQP_EUPEU             Reviewed;         229 AA.
AC   P23324;
DT   01-NOV-1991, integrated into UniProtKB/Swiss-Prot.
DT   10-AUG-2010, sequence version 2.
DT   25-MAY-2022, entry version 75.
DE   RecName: Full=Polyubiquitin;
DE   Contains:
DE     RecName: Full=Ubiquitin;
DE   Flags: Precursor;
OS   Euplotes eurystomus (Ciliate).
OC   Eukaryota; Sar; Alveolata; Ciliophora; Intramacronucleata; Spirotrichea;
OC   Hypotrichia; Euplotida; Euplotidae; Euplotes.
OX   NCBI_TaxID=5941;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=1654239; DOI=10.1007/bf00337517;
RA   Hauser L.J., Roberson A.E., Olins D.E.;
RT   "Structure of the macronuclear polyubiquitin gene in Euplotes.";
RL   Chromosoma 100:386-394(1991).
CC   -!- FUNCTION: Ubiquitin exists either covalently attached to another
CC       protein, or free (unanchored). When covalently bound, it is conjugated
CC       to target proteins via an isopeptide bond either as a monomer
CC       (monoubiquitin), a polymer linked via different Lys residues of the
CC       ubiquitin (polyubiquitin chains) or a linear polymer linked via the
CC       initiator Met of the ubiquitin (linear polyubiquitin chains).
CC       Polyubiquitin chains, when attached to a target protein, have different
CC       functions depending on the Lys residue of the ubiquitin that is linked:
CC       Lys-48-linked is involved in protein degradation via the proteasome.
CC       Linear polymer chains formed via attachment by the initiator Met lead
CC       to cell signaling. Ubiquitin is usually conjugated to Lys residues of
CC       target proteins, however, in rare cases, conjugation to Cys or Ser
CC       residues has been observed. When polyubiquitin is free (unanchored-
CC       polyubiquitin), it also has distinct roles, such as in activation of
CC       protein kinases, and in signaling (By similarity). {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Cytoplasm {ECO:0000250}. Nucleus {ECO:0000250}.
CC   -!- MISCELLANEOUS: For the sake of clarity sequence features are annotated
CC       only for the first chain, and are not repeated for each of the
CC       following chains.
CC   -!- SIMILARITY: Belongs to the ubiquitin family. {ECO:0000305}.
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DR   EMBL; M57231; AAA62225.1; -; Genomic_DNA.
DR   PIR; A56582; A56582.
DR   AlphaFoldDB; P23324; -.
DR   SMR; P23324; -.
DR   GO; GO:0005737; C:cytoplasm; IEA:UniProtKB-SubCell.
DR   GO; GO:0005634; C:nucleus; IEA:UniProtKB-SubCell.
DR   InterPro; IPR000626; Ubiquitin-like_dom.
DR   InterPro; IPR029071; Ubiquitin-like_domsf.
DR   InterPro; IPR019954; Ubiquitin_CS.
DR   InterPro; IPR019956; Ubiquitin_dom.
DR   Pfam; PF00240; ubiquitin; 3.
DR   PRINTS; PR00348; UBIQUITIN.
DR   SMART; SM00213; UBQ; 3.
DR   SUPFAM; SSF54236; SSF54236; 3.
DR   PROSITE; PS00299; UBIQUITIN_1; 3.
DR   PROSITE; PS50053; UBIQUITIN_2; 3.
PE   3: Inferred from homology;
KW   Cytoplasm; Isopeptide bond; Nucleus; Repeat; Ubl conjugation.
FT   CHAIN           1..76
FT                   /note="Ubiquitin"
FT                   /id="PRO_0000114824"
FT   CHAIN           77..152
FT                   /note="Ubiquitin"
FT                   /id="PRO_0000396359"
FT   CHAIN           153..228
FT                   /note="Ubiquitin"
FT                   /id="PRO_0000396360"
FT   PROPEP          229
FT                   /id="PRO_0000396361"
FT   DOMAIN          1..76
FT                   /note="Ubiquitin-like 1"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00214"
FT   DOMAIN          77..152
FT                   /note="Ubiquitin-like 2"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00214"
FT   DOMAIN          153..228
FT                   /note="Ubiquitin-like 3"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00214"
FT   CROSSLNK        48
FT                   /note="Glycyl lysine isopeptide (Lys-Gly) (interchain with
FT                   G-Cter in ubiquitin)"
FT                   /evidence="ECO:0000250"
FT   CROSSLNK        76
FT                   /note="Glycyl lysine isopeptide (Gly-Lys) (interchain with
FT                   K-? in acceptor proteins)"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00214"
SQ   SEQUENCE   229 AA;  25857 MW;  1174867897C3EADC CRC64;
     MQIFVKTLTG KTITLDVEQS DTIDNVKTKI QDKEGIPPDQ QRLIFAGKQL EDGRTLADYN
     IQKESTLHLV LRLRGGMQIF VKTLTGKTIT LDVEQSDTID NVKTKIQDKE GIPPDQQRLI
     FAGKQLEDGR TLADYNIQKE STLHLVLRLR GGMQIFVKTL TGKTITLDVE QSDTIDNVKT
     KIQDKEGIPP DQQRLIFAGK QLEDGRTLAD YNIQKESTLH LVLRLRGGF