ID   HBSAG_DHBV1             Reviewed;         328 AA.
AC   P03145;
DT   21-JUL-1986, integrated into UniProtKB/Swiss-Prot.
DT   23-JAN-2007, sequence version 4.
DT   10-JUN-2026, entry version 106.
DE   RecName: Full=Large envelope protein;
DE   AltName: Full=L glycoprotein;
DE   AltName: Full=L-HBsAg;
DE            Short=LHB;
DE   AltName: Full=Large S protein;
DE   AltName: Full=Large surface protein;
DE   AltName: Full=Major surface antigen;
DE   Contains:
DE     RecName: Full=Truncated S protein;
DE              Short=St;
GN   Name=S;
OS   Duck hepatitis B virus (strain United States/DHBV-16) (DHBV).
OC   Viruses; Riboviria; Pararnavirae; Artverviricota; Revtraviricetes;
OC   Blubervirales; Hepadnaviridae; Avihepadnavirus;
OC   Avihepadnavirus anatigruidae; Duck hepatitis B virus.
OX   NCBI_TaxID=489543;
OH   NCBI_TaxID=8835; Anas (ducks).
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=6699938; DOI=10.1128/jvi.49.3.782-792.1984;
RA   Mandart E., Kay A., Galibert F.;
RT   "Nucleotide sequence of a cloned duck hepatitis B virus genome: comparison
RT   with woodchuck and human hepatitis B virus sequences.";
RL   J. Virol. 49:782-792(1984).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=Isolate DHBV F1-6;
RX   PubMed=2235507; DOI=10.1093/nar/18.20.6140;
RA   Mattes F., Tong S., Teubner K., Blum H.E.;
RT   "Complete nucleotide sequence of a German duck hepatitis B virus.";
RL   Nucleic Acids Res. 18:6140-6140(1990).
RN   [3]
RP   MYRISTOYLATION AT GLY-2.
RX   PubMed=1994583; DOI=10.1016/0042-6822(91)90503-4;
RA   Macrae D.R., Bruss V., Ganem D.;
RT   "Myristylation of a duck hepatitis B virus envelope protein is essential
RT   for infectivity but not for virus assembly.";
RL   Virology 181:359-363(1991).
RN   [4]
RP   PHOSPHORYLATION.
RX   PubMed=7933117; DOI=10.1128/jvi.68.11.7344-7350.1994;
RA   Grgacic E.V., Anderson D.A.;
RT   "The large surface protein of duck hepatitis B virus is phosphorylated in
RT   the pre-S domain.";
RL   J. Virol. 68:7344-7350(1994).
RN   [5]
RP   PHOSPHORYLATION AT SER-118, AND MUTAGENESIS OF SER-118.
RX   PubMed=9820150; DOI=10.1099/0022-1317-79-11-2743;
RA   Grgacic E.V., Lin B., Gazina E.V., Snooks M.J., Anderson D.A.;
RT   "Normal phosphorylation of duck hepatitis B virus L protein is dispensable
RT   for infectivity.";
RL   J. Gen. Virol. 79:2743-2751(1998).
RN   [6]
RP   MUTAGENESIS OF 185-LYS--GLU-188.
RX   PubMed=12075081; DOI=10.1099/0022-1317-83-7-1635;
RA   Grgacic E.V.;
RT   "Identification of structural determinants of the first transmembrane
RT   domain of the small envelope protein of duck hepatitis B virus essential
RT   for particle morphogenesis.";
RL   J. Gen. Virol. 83:1635-1644(2002).
RN   [7]
RP   CHARACTERIZATION OF TRUNCATED S PROTEIN.
RX   PubMed=15827149; DOI=10.1128/jvi.79.9.5346-5352.2005;
RA   Grgacic E.V., Anderson D.A.;
RT   "St, a truncated envelope protein derived from the S protein of duck
RT   hepatitis B virus, acts as a chaperone for the folding of the large
RT   envelope protein.";
RL   J. Virol. 79:5346-5352(2005).
CC   -!- FUNCTION: The large envelope protein exists in two topological
CC       conformations, one which is termed 'external' or Le-HBsAg and the other
CC       'internal' or Li-HBsAg. In its external conformation the protein
CC       attaches the virus to cell receptors and thereby initiating infection.
CC       This interaction determines the species specificity and liver tropism.
CC       The large envelope protein probably also assumes fusion between virion
CC       and host membranes. In its internal conformation the protein plays a
CC       role in virion morphogenesis and mediates the contact with the
CC       nucleocapsid like a matrix protein (By similarity). {ECO:0000250}.
CC   -!- FUNCTION: Truncated S protein may be involved in translocation of pre-S
CC       domain through the virion membrane.
CC   -!- SUBUNIT: Large internal envelope protein interacts with capsid protein.
CC       {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Virion membrane.
CC   -!- ALTERNATIVE PRODUCTS:
CC       Event=Alternative initiation; Named isoforms=2;
CC       Name=L; Synonyms=Large envelope protein, LHB, L-HBsAg;
CC         IsoId=P03145-1; Sequence=Displayed;
CC       Name=S; Synonyms=Small envelope protein, SHB, S-HBsAg;
CC         IsoId=P03145-2; Sequence=VSP_031887;
CC   -!- DOMAIN: The large envelope protein is synthesized with the pre-S region
CC       at the cytosolic side of the endoplasmic reticulum and, hence will be
CC       within the virion after budding. Therefore the pre-S region is not N-
CC       glycosylated. Later a post-translational translocation of N-terminal
CC       pre-S and TM1 domains occur in about 50% of proteins at the virion
CC       surface. These molecules change their topology by an unknown mechanism,
CC       resulting in exposure of pre-S region at virion surface.
CC   -!- PTM: Myristoylation contributes importantly to DHBV infectivity. It is
CC       most likely required for an early step of the life cycle involving the
CC       entry or uncoating of virus particles. {ECO:0000269|PubMed:1994583}.
CC   -!- PTM: Phosphorylated on pre-S domain for about 50% of L proteins, the L
CC       chains with internal pre-S region (Li-HBsAg).
CC       {ECO:0000269|PubMed:7933117, ECO:0000269|PubMed:9820150}.
CC   -!- PTM: Isoform S may be cleaved by a cellular protease to produce
CC       truncated S protein.
CC   -!- SIMILARITY: Belongs to the avihepadnavirus major surface antigen
CC       family. {ECO:0000305}.
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DR   EMBL; X12798; CAB57224.1; -; Genomic_DNA.
DR   SMR; P03145; -.
DR   GlyCosmos; P03145; 1 site, No reported glycans.
DR   iPTMnet; P03145; -.
DR   GO; GO:0019031; C:viral envelope; IEA:UniProtKB-KW.
DR   GO; GO:0055036; C:virion membrane; IEA:UniProtKB-SubCell.
DR   GO; GO:0039663; P:membrane fusion involved in viral entry into host cell; IEA:UniProtKB-KW.
DR   GO; GO:0046718; P:symbiont entry into host cell; IEA:UniProtKB-KW.
DR   GO; GO:0019062; P:virion attachment to host cell; IEA:UniProtKB-KW.
DR   InterPro; IPR000349; HBV_HBSAG.
DR   Pfam; PF00695; vMSA; 1.
PE   1: Evidence at protein level;
KW   Alternative initiation; Fusion of virus membrane with host membrane;
KW   Glycoprotein; Host-virus interaction; Lipoprotein; Membrane; Myristate;
KW   Phosphoprotein; Transmembrane; Transmembrane helix;
KW   Viral attachment to host cell; Viral envelope protein;
KW   Viral penetration into host cytoplasm; Virion; Virus entry into host cell.
FT   INIT_MET        1
FT                   /note="Removed; by host"
FT                   /evidence="ECO:0000250"
FT   CHAIN           2..328
FT                   /note="Large envelope protein"
FT                   /id="PRO_0000038075"
FT   CHAIN           162..?238
FT                   /note="Truncated S protein"
FT                   /id="PRO_0000322196"
FT   TOPO_DOM        2..236
FT                   /note="Cytoplasmic; in internal conformation"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        2..163
FT                   /note="Extracellular; in external conformation"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        164..184
FT                   /note="Helical; Name=TM1; Note=In external conformation"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        185..236
FT                   /note="Cytoplasmic; in external conformation"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        237..257
FT                   /note="Helical; Name=TM2"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        258..282
FT                   /note="Extracellular"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        283..303
FT                   /note="Helical; Name=TM3"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        304..328
FT                   /note="Cytoplasmic"
FT                   /evidence="ECO:0000255"
FT   REGION          2..161
FT                   /note="Pre-S"
FT   REGION          63..128
FT                   /note="Disordered"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   COMPBIAS        76..88
FT                   /note="Polar residues"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   COMPBIAS        92..109
FT                   /note="Basic and acidic residues"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   SITE            ?238..?239
FT                   /note="Cleavage; by host"
FT                   /evidence="ECO:0000255"
FT   MOD_RES         118
FT                   /note="Phosphoserine; by host"
FT                   /evidence="ECO:0000269|PubMed:9820150"
FT   LIPID           2
FT                   /note="N-myristoyl glycine; by host"
FT                   /evidence="ECO:0000269|PubMed:1994583"
FT   CARBOHYD        260
FT                   /note="N-linked (GlcNAc...) asparagine; by host"
FT                   /evidence="ECO:0000255"
FT   VAR_SEQ         1..161
FT                   /note="Missing (in isoform S)"
FT                   /evidence="ECO:0000305"
FT                   /id="VSP_031887"
FT   MUTAGEN         118
FT                   /note="S->A: 64% loss of phosphorylation."
FT                   /evidence="ECO:0000269|PubMed:9820150"
FT   MUTAGEN         185..188
FT                   /note="KILE->AILA: Complete loss of pre-S domain
FT                   translocation."
FT                   /evidence="ECO:0000269|PubMed:12075081"
SQ   SEQUENCE   328 AA;  36230 MW;  B2D771241E407456 CRC64;
     MGQHPAKSMD VRRIEGGEIL LNQLAGRMIP KGTLTWSGKF PTLDHVLDHV QTMEEINTLQ
     NQGAWPAGAG RRVGLSNPTP QEIPQPQWTP EEDQKAREAF RRYQEERPPE TTTIPPSSPP
     QWKLQPGDDP LLGNQSLLET HPLYQSEPAV PVIKTPPLKK KMSGTFGGIL AGLIGLLVSF
     FLLIKILEIL RRLDWWWISL SSPKGKMQCA FQDTGAQISP HYVGSCPWGC PGFLWTYLRL
     FIIFLLILLV AAGLLYLTDN GSTILGKLQW ASVSALFSSI SSLLPSDPKS LVALTFGLSL
     IWMTSSSATQ TLVTLTQLAT LSALFYKS
//