Q9QBF0 · HBSAG_HBVB7

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

AspectTerm
Cellular Componentmembrane
Cellular Componentviral envelope
Cellular Componentvirion membrane
Biological Processcaveolin-mediated endocytosis of virus by host cell
Biological Processfusion of virus membrane with host endosome membrane
Biological Processvirion attachment to host cell

Keywords

Names & Taxonomy

Protein names

  • Recommended name
    Large envelope protein
  • Alternative names
    • L glycoprotein
    • L-HBsAg
      (LHB
      )
    • Large S protein
    • Large surface protein
    • Major surface antigen

Gene names

    • Name
      S

Organism names

Accessions

  • Primary accession
    Q9QBF0
  • Secondary accessions
    • Q9QBF3

Proteomes

Subcellular Location

Features

Showing features for topological domain, transmembrane.

TypeIDPosition(s)Description
Topological domain2-181Virion surface; in external conformation
Topological domain2-253Intravirion; in internal conformation
Transmembrane182-202Helical; Name=TM1; Note=In external conformation
Topological domain203-253Intravirion; in external conformation
Transmembrane254-274Helical; Name=TM2
Topological domain275-348Virion surface
Transmembrane349-369Helical
Topological domain370-375Intravirion
Transmembrane376-398Helical; Name=TM3
Topological domain399-400Virion surface

Keywords

Phenotypes & Variants

PTM/Processing

Features

Showing features for initiator methionine, lipidation, chain, glycosylation.

TypeIDPosition(s)Description
Initiator methionine1Removed; by host
Lipidation2N-myristoyl glycine; by host
ChainPRO_00003190782-400Large envelope protein
Glycosylation320N-linked (GlcNAc...) asparagine; by host

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 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.

Structure

3D structure databases

Family & Domains

Features

Showing features for region, compositional bias.

TypeIDPosition(s)Description
Region1-50Disordered
Region2-119Pre-S1
Region2-174Pre-S
Compositional bias84-108Polar residues
Region84-116Disordered
Region120-174Pre-S2

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

Family and domain databases

Sequence & Isoform

Align isoforms (2)
  • Sequence status
    Complete

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.

  • Name
    L
  • Synonyms
    Large envelope protein, LHB, L-HBsAg
  • See also
    sequence in UniParc or sequence clusters in UniRef
  • Length
    400
  • Mass (Da)
    43,595
  • Last updated
    2000-05-01 v1
  • Checksum
    29A2DE64DFE7B9EB
MGGWSSKPRKGMGTNLSVPNPLGFFPDHQLDPAFKANSENPDWDLNPHKDNWPDAHKVGVGAFGPGFTPPHGGLLGWSPQAQGILTSVPAAPPPASTNRQSGRQPTPLSPPLRDTHPQAVQWNSTTFHQTLQDPRVRALYLPAGGSSSGTVSPAQNTVSAISSILSTTGDPVPNMENIASGLLGPLLVLQAGFFSLTKILTIPQSLDSWWTSLNFLGGTPVCLGQNSQSQISSHSPTCCPPICPGYRWMCLRRFIIFLCILLLCLIFLLVLLDYQGMLPVCPLIPGSSTTSTGPCKTCTTPAQGTSMFPSCCCTKPTDGNCTCIPIPSSWAFAKYLWEWASVRFSWLSLLVPFVQWFVGLSPTVWLSVIWMMWFWGPSLYNILSPFMPLLPIFLCLWVYM

Q9QBF0-2

  • Name
    S
  • Synonyms
    Small envelope protein, SHB, S-HBsAg
  • See also
    sequence in UniParc or sequence clusters in UniRef
  • Differences from canonical

Features

Showing features for alternative sequence, compositional bias.

TypeIDPosition(s)Description
Alternative sequenceVSP_0313791-174in isoform S
Compositional bias84-108Polar residues

Keywords

Sequence databases

Nucleotide SequenceProtein SequenceMolecule TypeStatus
AB010290
EMBL· GenBank· DDBJ
BAA88282.1
EMBL· GenBank· DDBJ
Genomic DNA
AB010290
EMBL· GenBank· DDBJ
BAA88278.1
EMBL· GenBank· DDBJ
Genomic DNA

Similar Proteins

Disclaimer

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