AC   MF_04075;
DC   Protein; auto
TR   HAMAP; MF_04075; -; 1; level=0
XX
Names: HBV_HBSAG
XX
ID   HBSAG
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;
GN   Name=S;
XX
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       This attachment induces virion internalization predominantly through
CC       caveolin-mediated endocytosis. The large envelope protein also assures
CC       fusion between virion membrane and endosomal membrane. In its internal
CC       conformation the protein plays a role in virion morphogenesis and
CC       mediates the contact with the nucleocapsid like a matrix protein.
CC   -!- FUNCTION: The middle envelope protein plays an important role in the
CC       budding of the virion. It is involved in the induction of budding in a
CC       nucleocapsid independent way. In this process the majority of envelope
CC       proteins bud to form subviral lipoprotein particles of 22 nm of
CC       diameter that do not contain a nucleocapsid.
CC   -!- SUBCELLULAR LOCATION: Virion membrane.
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. For isoform M
CC       in contrast, the pre-S2 region is translocated cotranslationally to the
CC       endoplasmic reticulum lumen and is N-glycosylated.
CC   -!- PTM: Isoform M is N-terminally acetylated by host at a ratio of 90%,
CC       and N-glycosylated by host at the pre-S2 region.
CC   -!- PTM: Myristoylated.
CC   -!- SIMILARITY: Belongs to the orthohepadnavirus major surface antigen
CC       family.
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DR   PROSITE; PS00001; ASN_GLYCOSYLATION; 0-unlimited; trigger=yes
DR   Pfam; PF00695; vMSA; 1; trigger=no
DR   General; Transmembrane; -; 4; trigger=no
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KW   Acetylation
KW   Caveolin-mediated endocytosis of virus by host
KW   Fusion of virus membrane with host endosomal membrane
KW   Fusion of virus membrane with host membrane
KW   Glycoprotein
KW   Host-virus interaction
KW   Lipoprotein
KW   Membrane
KW   Myristate
KW   Transmembrane
KW   Transmembrane helix
KW   Viral attachment to host cell
KW   Viral penetration into host cytoplasm
KW   Virion
KW   Virus endocytosis by host
KW   Virus entry into host cell
XX
GO   GO:0016020; C:membrane
GO   GO:0055036; C:virion membrane
GO   GO:0039663; P:membrane fusion involved in viral entry into host cell
GO   GO:0019062; P:virion attachment to host cell
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FT   From: HBSAG_HBVCJ (Q76R62)
FT   INIT_MET        Nter
FT                   /note="Removed; by host"
FT   Condition: M
FT   CHAIN           Nter+1..Cter
FT                   /note="Large envelope protein"
FT   TOPO_DOM        Nter+1..253
FT                   /note="Intravirion; in internal conformation"
FT   TOPO_DOM        Nter+1..181
FT                   /note="Virion surface; in external conformation"
FT   TRANSMEM        182..202
FT                   /note="Helical; Name=TM1; Note=In external conformation"
FT   TOPO_DOM        203..253
FT                   /note="Intravirion; in external conformation"
FT   TRANSMEM        254..274
FT                   /note="Helical; Name=TM2"
FT   TOPO_DOM        275..348
FT                   /note="Virion surface"
FT   TRANSMEM        349..369
FT                   /note="Helical"
FT   TOPO_DOM        370..375
FT                   /note="Intravirion"
FT   TRANSMEM        376..398
FT                   /note="Helical; Name=TM3"
FT   TOPO_DOM        399..Cter
FT                   /note="Virion surface"
FT   REGION          Nter+1..174
FT                   /note="Pre-S"
FT   REGION          Nter+1..119
FT                   /note="Pre-S1"
FT   REGION          120..174
FT                   /note="Pre-S2"
FT   LIPID           Nter+1
FT                   /note="N-myristoyl glycine; by host"
FT   Condition: G
XX
Size: 389-431;
Related: None;
Template: Q76R62;
Scope:
 Viruses; Orthohepadnavirus
Fusion:
 Nter: None
 Cter: None
Duplicate: None
Plasmid: None
Comments: None
XX
# Revision 1.6 2022/09/29
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