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Annotation rule MF_04075
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General rule information [?]

Accession MF_04075
Dates 11-MAY-2017 (Created)
4-DEC-2019 (Last updated, Version 5)
Viruses; Orthohepadnavirus
Template Q76R62 (HBSAG_HBVCJ)

Propagated annotation [?]

Identifier, protein and gene names [?]

Protein name
RecName: Full=Large envelope protein;
AltName: Full=L glycoprotein;
AltName: Full=L-HBsAg;
AltName: Full=Large S protein;
AltName: Full=Large surface protein;
AltName: Full=Major surface antigen;
Gene name

Comments [?]

Function The large envelope protein exists in two topological conformations, one which is termed 'external' or Le-HBsAg and the other 'internal' or Li-HBsAg. In its external conformation the protein attaches the virus to cell receptors and thereby initiating infection. This interaction determines the species specificity and liver tropism. This attachment induces virion internalization predominantly through caveolin-mediated endocytosis. The large envelope protein also assures fusion between virion membrane and endosomal membrane. In its internal conformation the protein plays a role in virion morphogenesis and mediates the contact with the nucleocapsid like a matrix protein.
The middle envelope protein plays an important role in the budding of the virion. It is involved in the induction of budding in a nucleocapsid independent way. In this process the majority of envelope proteins bud to form subviral lipoprotein particles of 22 nm of diameter that do not contain a nucleocapsid.
Subcellular location Virion membrane.
Domain The large envelope protein is synthesized with the pre-S region at the cytosolic side of the endoplasmic reticulum and, hence will be within the virion after budding. Therefore the pre-S region is not N-glycosylated. Later a post-translational translocation of N-terminal pre-S and TM1 domains occur in about 50% of proteins at the virion surface. These molecules change their topology by an unknown mechanism, resulting in exposure of pre-S region at virion surface. For isoform M in contrast, the pre-S2 region is translocated cotranslationally to the endoplasmic reticulum lumen and is N-glycosylated.
Ptm Isoform M is N-terminally acetylated by host at a ratio of 90%, and N-glycosylated by host at the pre-S2 region.
Similarity Belongs to the orthohepadnavirus major surface antigen family.

Keywords [?]

Gene Ontology [?]

GO:0016021; Cellular component: integral component of membrane.
GO:0055036; Cellular component: virion membrane.
GO:0039663; Biological process: membrane fusion involved in viral entry into host cell.
GO:0019062; Biological process: virion attachment to host cell.

Cross-references [?]

PROSITE PS00001; ASN_GLYCOSYLATION; 0-unlimited; trigger=PRU00498;
Pfam PF00695; vMSA; 1;

Computed features [?]

General Transmembrane; -; 4;

Features [?]

From: HBSAG_HBVCJ (Q76R62)
Key     From     To       Description   Tag   Condition   FTGroup
INIT_MET     Nter     Nter       Removed; by host     M  
CHAIN     Nter+1     Cter       Large envelope protein        
TOPO_DOM     Nter+1     253       Intravirion; in internal conformation        
TOPO_DOM     Nter+1     181       Virion surface; in external conformation        
TRANSMEM     182     202       Helical; Name=TM1; Note=In external conformation        
TOPO_DOM     203     253       Intravirion; in external conformation        
TRANSMEM     254     274       Helical; Name=TM2        
TOPO_DOM     275     348       Virion surface        
TRANSMEM     349     369       Helical        
TOPO_DOM     370     375       Intravirion        
TRANSMEM     376     398       Helical; Name=TM3        
TOPO_DOM     399     Cter       Virion surface        
REGION     Nter+1     174       Pre-S        
REGION     Nter+1     119       Pre-S1        
REGION     120     174       Pre-S2        
LIPID     Nter+1     Nter+1       N-myristoyl glycine; by host     G  

Additional information [?]

Size range 389-431 amino acids
Related rules None
Fusion None