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If a protein meets these conditions... i

Common conditions

Special conditions

    • Subsequence at position 120 - 174 aligns to entry Q76R62 (individually applies "Pre-S2")
    • Subsequence at position 203 - 253 aligns to entry Q76R62 (individually applies "Intravirion; in external conformation")
    • Subsequence at position 275 - 348 aligns to entry Q76R62 (individually applies "Virion surface")
    • Subsequence at position 370 - 375 aligns to entry Q76R62 (individually applies "Intravirion")
    • Subsequence at position 399 - @CTER|+1@ aligns to entry Q76R62 (individually applies "Virion surface")
    • Subsequence at position @NTER|+1@ - @NTER|+1@ aligns to "M" in entry Q76R62 (individually applies "Removed; by host")
    • Subsequence at position @PLUS|+1@ - 119 aligns to entry Q76R62 (individually applies "Pre-S1")
    • Subsequence at position @PLUS|+1@ - 174 aligns to entry Q76R62 (individually applies "Pre-S")
    • Subsequence at position @PLUS|+1@ - 181 aligns to entry Q76R62 (individually applies "Virion surface; in external conformation")
    • Subsequence at position @PLUS|+1@ - 253 aligns to entry Q76R62 (individually applies "Intravirion; in internal conformation")
    • Subsequence at position @PLUS|+1@ - @PLUS|+1@ aligns to "G" in entry Q76R62 (individually applies "N-myristoyl glycine; by host")

... then these annotations are applied i

Protein namei

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

Gene namei

  • Name:S

Sequence similaritiesi

Functioni

  • 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.

Post-translational modificationi

  • Isoform M is N-terminally acetylated by host at a ratio of 90%, and N-glycosylated by host at the pre-S2 region.
  • Myristoylated.

Subcellular locationi

Subunit structurei

  • 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.

Domaini

  • 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.

Regioni

  • Pre-S2 (to residues corresponding to positions 120 - 174)
  • Pre-S1 (to residues corresponding to positions @PLUS|+1@i - 119)
  • Pre-S (to residues corresponding to positions @PLUS|+1@i - 174)

Initiator methioninei

  • Removed; by host (to residues corresponding to position @NTER|+1@i)

Topological domaini

  • Intravirion; in external conformation (to residues corresponding to positions 203 - 253)
  • Virion surface (to residues corresponding to positions 275 - 348)
  • Intravirion (to residues corresponding to positions 370 - 375)
  • Virion surface (to residues corresponding to positions 399 - @CTER|+1@i)
  • Virion surface; in external conformation (to residues corresponding to positions @PLUS|+1@i - 181)
  • Intravirion; in internal conformation (to residues corresponding to positions @PLUS|+1@i - 253)

Lipidationi

  • N-myristoyl glycine; by host (to residues corresponding to position @PLUS|+1@i)

Keywordsi

GO (Gene Ontology) termsi