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HAMAP rule MF_04076

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General rule information [?]

Accession MF_04076
Dates 15-MAY-2017 (Created)
3-MAY-2022 (Last updated, Version 8)
Viruses; Orthohepadnavirus
Templates P0C767 (HBEAG_HBVCJ); Q76R61 (CAPSD_HBVCJ): [Recover all]

Propagated annotation [?]

Identifier, protein and gene names [?]

case <FTTag:HBEAG>
Protein name
RecName: Full=External core antigen;
AltName: Full=HBeAg;
AltName: Full=Precore protein;
AltName: Full=p25;
Flags: Precursor;
Gene name
Protein name
RecName: Full=Capsid protein;
AltName: Full=Core antigen;
AltName: Full=Core protein;
AltName: Full=HBcAg;
AltName: Full=p21.5;
Gene name
end case

Comments [?]

case <FTTag:HBEAG>
Function May regulate immune response to the intracellular capsid in acting as a T-cell tolerogen, by having an immunoregulatory effect which prevents destruction of infected cells by cytotoxic T-cells. This immune regulation may predispose to chronicity during perinatal infections and prevent severe liver injury during adult infections.
Subunit Homodimerizes.
Subcellular location Secreted. Host nucleus.
Ptm Phosphorylated.
Cleaved by host furin.
Similarity Belongs to the orthohepadnavirus precore antigen family.
Function Self assembles to form an icosahedral capsid. Most capsids appear to be large particles with an icosahedral symmetry of T=4 and consist of 240 copies of capsid protein, though a fraction forms smaller T=3 particles consisting of 180 capsid proteins. Entering capsids are transported along microtubules to the nucleus. Phosphorylation of the capsid is thought to induce exposure of nuclear localization signal in the C-terminal portion of the capsid protein that allows binding to the nuclear pore complex via the importin (karyopherin-) alpha and beta. Capsids are imported in intact form through the nuclear pore into the nuclear basket, where it probably binds NUP153. Only capsids that contain the mature viral genome can release the viral DNA and capsid protein into the nucleoplasm. Immature capsids get stuck in the basket. Capsids encapsulate the pre-genomic RNA and the P protein. Pre-genomic RNA is reverse-transcribed into DNA while the capsid is still in the cytoplasm. The capsid can then either be directed to the nucleus, providing more genomes for transcription, or bud through the endoplasmic reticulum to provide new virions.
Subunit Homodimerizes, then multimerizes. Interacts with cytosol exposed regions of viral L glycoprotein present in the reticulum-to-Golgi compartment. Interacts with human FLNB. Phosphorylated form interacts with host importin alpha; this interaction depends on the exposure of the NLS, which itself depends upon genome maturation and/or phosphorylation of the capsid protein. Interacts with host NUP153.
Subcellular location Virion. Host cytoplasm.
Ptm Phosphorylated by host SRPK1, SRPK2, and maybe protein kinase C or GAPDH. Phosphorylation is critical for pregenomic RNA packaging. Protein kinase C phosphorylation is stimulated by HBx protein and may play a role in transport of the viral genome to the nucleus at the late step during the viral replication cycle.
Similarity Belongs to the orthohepadnavirus core antigen family.
end case

Keywords [?]

case <FTTag:HBEAG>
end case

Gene Ontology [?]

case <FTTag:HBEAG>
GO:0005576; Cellular component: extracellular region.
GO:0042025; Cellular component: host cell nucleus.
GO:0019049; Biological process: mitigation of host antiviral defense response.
GO:0030430; Cellular component: host cell cytoplasm.
GO:0039619; Cellular component: T=4 icosahedral viral capsid.
GO:0003677; Molecular function: DNA binding.
GO:0003723; Molecular function: RNA binding.
GO:0075521; Biological process: microtubule-dependent intracellular transport of viral material towards nucleus.
GO:0046718; Biological process: viral entry into host cell.
GO:0075732; Biological process: viral penetration into host nucleus.
end case
GO:0005198; Molecular function: structural molecule activity.

Cross-references [?]

Pfam PF08290; Hep_core_N; 0-1;
PF00906; Hepatitis_core; 2-3;

Computed features [?]

case <FTTag:HBEAG>
General Signal; -; 1; trigger=yes;
end case

Features [?]

From: HBEAG_HBVCJ (P0C767)
Key     From     To       Description   Tag   Condition   FTGroup
REGION     25     27       HBEAG   HBEAG   G-W-L  
case <FTTag:HBEAG>
SITE     183     184       Cleavage; by host     R-S  
DISULFID     77     77       Interchain     C  
DISULFID     90     90       Interchain     C  
From: CAPSD_HBVCJ (Q76R61)
REGION     177     183       RNA binding        
MOTIF     158     175       Bipartite nuclear localization signal        
MOD_RES     155     155       Phosphoserine; by host     S  
MOD_RES     162     162       Phosphoserine; by host     S  
MOD_RES     170     170       Phosphoserine; by host     S  
end case

Additional information [?]

Size range 182-218 amino acids
Related rules None
Fusion None