ID   HBEAG_HPBDW             Reviewed;         305 AA.
AC   P17191;
DT   01-AUG-1990, integrated into UniProtKB/Swiss-Prot.
DT   01-MAY-1991, sequence version 2.
DT   10-JUN-2026, entry version 76.
DE   RecName: Full=External core antigen;
DE   AltName: Full=HBeAg;
DE   AltName: Full=Precore protein;
DE   Flags: Precursor;
GN   Name=C;
OS   Duck hepatitis B virus (isolate white Shanghai duck S31) (DHBV).
OC   Viruses; Riboviria; Pararnavirae; Artverviricota; Revtraviricetes;
OC   Blubervirales; Hepadnaviridae; Avihepadnavirus;
OC   Avihepadnavirus anatigruidae; Duck hepatitis B virus.
OX   NCBI_TaxID=10440;
OH   NCBI_TaxID=8835; Anas (ducks).
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=2596031; DOI=10.1016/0042-6822(89)90571-0;
RA   Uchida M., Esumi M., Shikata T.;
RT   "Molecular cloning and sequence analysis of duck hepatitis B virus genomes
RT   of a new variant isolated from Shanghai ducks.";
RL   Virology 173:600-606(1989).
CC   -!- FUNCTION: May regulate immune response to the intracellular capsid in
CC       acting as a T-cell tolerogen, by having an immunoregulatory effect
CC       which prevents destruction of infected cells by cytotoxic T-cells.
CC       {ECO:0000250}.
CC   -!- SUBUNIT: Homodimerizes. {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000250}.
CC   -!- ALTERNATIVE PRODUCTS:
CC       Event=Alternative initiation; Named isoforms=2;
CC       Name=External core antigen;
CC         IsoId=P17191-1; Sequence=Displayed;
CC       Name=Capsid protein;
CC         IsoId=P0C6K2-1; Sequence=External;
CC   -!- SIMILARITY: Belongs to the avihepadnavirus precore antigen family.
CC       {ECO:0000305}.
CC   -!- SEQUENCE CAUTION:
CC       Sequence=AAA45750.1; Type=Erroneous initiation; Evidence={ECO:0000305};
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DR   EMBL; M32991; AAA45750.1; ALT_INIT; Genomic_DNA.
DR   PIR; F33746; NKVLWD.
DR   SMR; P17191; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0005198; F:structural molecule activity; IEA:InterPro.
DR   GO; GO:0052031; P:symbiont-mediated perturbation of host defense response; IEA:UniProtKB-KW.
DR   Gene3D; 1.10.4090.10; Viral capsid, core domain supefamily, Hepatitis B virus; 2.
DR   InterPro; IPR002006; Hepatitis_core.
DR   InterPro; IPR036459; Viral_capsid_core_dom_sf_HBV.
DR   Pfam; PF00906; Hepatitis_core; 1.
DR   SUPFAM; SSF47852; Hepatitis B viral capsid (hbcag); 1.
PE   3: Inferred from homology;
KW   Alternative initiation; Host-virus interaction; Secreted; Signal;
KW   Viral immunoevasion.
FT   SIGNAL          1..19
FT                   /evidence="ECO:0000255"
FT   CHAIN           20..272
FT                   /note="External core antigen"
FT                   /id="PRO_0000222305"
FT   PROPEP          273..305
FT                   /evidence="ECO:0000250"
FT                   /id="PRO_0000324685"
FT   REGION          226..305
FT                   /note="Disordered"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   COMPBIAS        258..277
FT                   /note="Basic residues"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   COMPBIAS        295..305
FT                   /note="Basic residues"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   SITE            272..273
FT                   /note="Cleavage; by host"
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   305 AA;  34929 MW;  3946D3FE7BE5E61E CRC64;
     MWNLRITPLS FGAACQGIFT STLLLSALTV PLVCTIVYDS CLYMDINASR ALANVYDLPD
     DFFPKIDDLV RDAKDALEPY WKSDSIKKHV LIATHFVDLI EDFWQTTQGM HEIAESLRAV
     IPPTTAPVPT GYLIQHEEAE EIPLGDLFKH QEERIVSFQP DYPITARIHA HLKAYAKINE
     ESLDRARRLL WWHYNCLLWG EANVTNYISR LRTWLSTPEK YRGRDAPTIE AITRPIQVAQ
     GGRKTSSGTR KPRGLEPRRR KVKTTFVYGR RRSKSRERRA PSPQRAGSPL PRSSSSHHRS
     PSPRK
//