Q9QBF0 · HBSAG_HBVB7
- ProteinLarge envelope protein
- GeneS
- StatusUniProtKB reviewed (Swiss-Prot)
- Amino acids400 (go to sequence)
- Protein existenceEvidence at protein level
- Annotation score4/5
Function
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.
Biotechnology
Systematic vaccination of individuals at risk of exposure to the virus has been the main method of controlling the morbidity and mortality associated with hepatitis B. The first hepatitis B vaccine was manufactured by the purification and inactivation of HBsAg obtained from the plasma of chronic hepatitis B virus carriers. The vaccine is now produced by recombinant DNA techniques and expression of the S isoform in yeast cells. The pre-S region do not seem to induce strong enough antigenic response.
GO annotations
Aspect | Term | |
---|---|---|
Cellular Component | membrane | |
Cellular Component | viral envelope | |
Cellular Component | virion membrane | |
Biological Process | caveolin-mediated endocytosis of virus by host cell | |
Biological Process | fusion of virus membrane with host endosome membrane | |
Biological Process | virion attachment to host cell |
Keywords
- Biological process
Names & Taxonomy
Protein names
- Recommended nameLarge envelope protein
- Alternative names
Gene names
Organism names
- Taxonomic lineageViruses > Riboviria > Pararnavirae > Artverviricota > Revtraviricetes > Blubervirales > Hepadnaviridae > Orthohepadnavirus > Hepatitis B virus
- Virus hosts
Accessions
- Primary accessionQ9QBF0
- Secondary accessions
Proteomes
Subcellular Location
UniProt Annotation
GO Annotation
Features
Showing features for topological domain, transmembrane.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Topological domain | 2-181 | Virion surface; in external conformation | ||||
Sequence: GGWSSKPRKGMGTNLSVPNPLGFFPDHQLDPAFKANSENPDWDLNPHKDNWPDAHKVGVGAFGPGFTPPHGGLLGWSPQAQGILTSVPAAPPPASTNRQSGRQPTPLSPPLRDTHPQAVQWNSTTFHQTLQDPRVRALYLPAGGSSSGTVSPAQNTVSAISSILSTTGDPVPNMENIASG | ||||||
Topological domain | 2-253 | Intravirion; in internal conformation | ||||
Sequence: GGWSSKPRKGMGTNLSVPNPLGFFPDHQLDPAFKANSENPDWDLNPHKDNWPDAHKVGVGAFGPGFTPPHGGLLGWSPQAQGILTSVPAAPPPASTNRQSGRQPTPLSPPLRDTHPQAVQWNSTTFHQTLQDPRVRALYLPAGGSSSGTVSPAQNTVSAISSILSTTGDPVPNMENIASGLLGPLLVLQAGFFSLTKILTIPQSLDSWWTSLNFLGGTPVCLGQNSQSQISSHSPTCCPPICPGYRWMCLRR | ||||||
Transmembrane | 182-202 | Helical; Name=TM1; Note=In external conformation | ||||
Sequence: LLGPLLVLQAGFFSLTKILTI | ||||||
Topological domain | 203-253 | Intravirion; in external conformation | ||||
Sequence: PQSLDSWWTSLNFLGGTPVCLGQNSQSQISSHSPTCCPPICPGYRWMCLRR | ||||||
Transmembrane | 254-274 | Helical; Name=TM2 | ||||
Sequence: FIIFLCILLLCLIFLLVLLDY | ||||||
Topological domain | 275-348 | Virion surface | ||||
Sequence: QGMLPVCPLIPGSSTTSTGPCKTCTTPAQGTSMFPSCCCTKPTDGNCTCIPIPSSWAFAKYLWEWASVRFSWLS | ||||||
Transmembrane | 349-369 | Helical | ||||
Sequence: LLVPFVQWFVGLSPTVWLSVI | ||||||
Topological domain | 370-375 | Intravirion | ||||
Sequence: WMMWFW | ||||||
Transmembrane | 376-398 | Helical; Name=TM3 | ||||
Sequence: GPSLYNILSPFMPLLPIFLCLWV | ||||||
Topological domain | 399-400 | Virion surface | ||||
Sequence: YM |
Keywords
- Cellular component
Phenotypes & Variants
PTM/Processing
Features
Showing features for initiator methionine, lipidation, chain, glycosylation.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Initiator methionine | 1 | Removed; by host | ||||
Sequence: M | ||||||
Lipidation | 2 | N-myristoyl glycine; by host | ||||
Sequence: G | ||||||
Chain | PRO_0000319078 | 2-400 | Large envelope protein | |||
Sequence: GGWSSKPRKGMGTNLSVPNPLGFFPDHQLDPAFKANSENPDWDLNPHKDNWPDAHKVGVGAFGPGFTPPHGGLLGWSPQAQGILTSVPAAPPPASTNRQSGRQPTPLSPPLRDTHPQAVQWNSTTFHQTLQDPRVRALYLPAGGSSSGTVSPAQNTVSAISSILSTTGDPVPNMENIASGLLGPLLVLQAGFFSLTKILTIPQSLDSWWTSLNFLGGTPVCLGQNSQSQISSHSPTCCPPICPGYRWMCLRRFIIFLCILLLCLIFLLVLLDYQGMLPVCPLIPGSSTTSTGPCKTCTTPAQGTSMFPSCCCTKPTDGNCTCIPIPSSWAFAKYLWEWASVRFSWLSLLVPFVQWFVGLSPTVWLSVIWMMWFWGPSLYNILSPFMPLLPIFLCLWVYM | ||||||
Glycosylation | 320 | N-linked (GlcNAc...) asparagine; by host | ||||
Sequence: N |
Post-translational modification
Isoform M is N-terminally acetylated by host at a ratio of 90%, and N-glycosylated by host at the pre-S2 region.
Myristoylated.
Keywords
- PTM
PTM databases
Interaction
Subunit
Li-HBsAg interacts with capsid protein and with HDV Large delta antigen. Isoform M associates with host chaperone CANX through its pre-S2 N glycan. This association may be essential for M proper secretion.
Family & Domains
Features
Showing features for region, compositional bias.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Region | 1-50 | Disordered | ||||
Sequence: MGGWSSKPRKGMGTNLSVPNPLGFFPDHQLDPAFKANSENPDWDLNPHKD | ||||||
Region | 2-119 | Pre-S1 | ||||
Sequence: GGWSSKPRKGMGTNLSVPNPLGFFPDHQLDPAFKANSENPDWDLNPHKDNWPDAHKVGVGAFGPGFTPPHGGLLGWSPQAQGILTSVPAAPPPASTNRQSGRQPTPLSPPLRDTHPQA | ||||||
Region | 2-174 | Pre-S | ||||
Sequence: GGWSSKPRKGMGTNLSVPNPLGFFPDHQLDPAFKANSENPDWDLNPHKDNWPDAHKVGVGAFGPGFTPPHGGLLGWSPQAQGILTSVPAAPPPASTNRQSGRQPTPLSPPLRDTHPQAVQWNSTTFHQTLQDPRVRALYLPAGGSSSGTVSPAQNTVSAISSILSTTGDPVPN | ||||||
Compositional bias | 84-108 | Polar residues | ||||
Sequence: ILTSVPAAPPPASTNRQSGRQPTPL | ||||||
Region | 84-116 | Disordered | ||||
Sequence: ILTSVPAAPPPASTNRQSGRQPTPLSPPLRDTH | ||||||
Region | 120-174 | Pre-S2 | ||||
Sequence: VQWNSTTFHQTLQDPRVRALYLPAGGSSSGTVSPAQNTVSAISSILSTTGDPVPN |
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.
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.
Sequence similarities
Belongs to the orthohepadnavirus major surface antigen family.
Keywords
- Domain
Family and domain databases
Sequence & Isoform
- Sequence statusComplete
This entry describes 2 isoforms produced by Alternative splicing & Alternative initiation.
Q9QBF0-1
This isoform has been chosen as the canonical sequence. All positional information in this entry refers to it. This is also the sequence that appears in the downloadable versions of the entry.
- NameL
- SynonymsLarge envelope protein, LHB, L-HBsAg
- Length400
- Mass (Da)43,595
- Last updated2000-05-01 v1
- Checksum29A2DE64DFE7B9EB
Q9QBF0-2
- NameS
- SynonymsSmall envelope protein, SHB, S-HBsAg
- Differences from canonical
- 1-174: Missing
Features
Showing features for alternative sequence, compositional bias.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Alternative sequence | VSP_031379 | 1-174 | in isoform S | |||
Sequence: Missing | ||||||
Compositional bias | 84-108 | Polar residues | ||||
Sequence: ILTSVPAAPPPASTNRQSGRQPTPL |
Keywords
- Coding sequence diversity