Q9QMI2 · CAPSD_HBVD4

Function

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.

GO annotations

all annotationsall molecular functionvirus receptor activitydna bindingrna bindingcytoskeletal motor activitycatalytic activitygtpase activitystructural molecule activitytransporter activitycytoskeletal protein bindinglipid bindingcyclase activityantioxidant activityoxidoreductase activitytransferase activityhydrolase activitylyase activityisomerase activityligase activityprotein tag activitycargo receptor activityhistone bindingprotein folding chaperonetranslation regulator activitynutrient reservoir activityreceptor ligand activitymolecular transducer activitymolecular adaptor activitytoxin activitycell adhesion mediator activitymolecular function regulator activityvirus coreceptor activitycatalytic activity, acting on a proteincatalytic activity, acting on dnacatalytic activity, acting on rnamolecular carrier activitytranscription regulator activitygeneral transcription initiation factor activitymolecular sensor activitymolecular sequestering activityatp-dependent activityother molecular functionall biological processmitotic cell cyclecytokinesiscytoplasmic translationimmune system processmuscle system processcirculatory system processrenal system processrespiratory system processcarbohydrate metabolic processgeneration of precursor metabolites and energydna replicationdna repairdna recombinationchromatin organizationdna-templated transcriptionregulation of dna-templated transcriptiontrna metabolic processprotein foldingprotein glycosylationamino acid metabolic processmodified amino acid metabolic processlipid metabolic processvitamin metabolic processsulfur compound metabolic processintracellular protein transportnucleocytoplasmic transportautophagyinflammatory responsemitochondrion organizationcytoskeleton organizationmicrotubule-based movementperoxisome organizationlysosome organizationchromosome segregationcell adhesionestablishment or maintenance of cell polarityprogrammed cell deathphotosynthesismrna metabolic processsnrna metabolic processvesicle-mediated transportreproductive processdigestive system processsignalingcell differentiationprotein catabolic processextracellular matrix organizationregulatory ncrna-mediated gene silencingtelomere organizationcell junction organizationwound healingribosome biogenesiscilium organizationanatomical structure developmentcell motilitynervous system processendocrine processprotein maturationtransmembrane transportnucleobase-containing small molecule metabolic processhepaticobiliary system processmembrane organizationprotein-containing complex assemblycell wall organization or biogenesisnitrogen cycle metabolic processprotein localization to plasma membranedefense response to other organismdetoxificationmeiotic nuclear divisionmitotic nuclear divisionmitochondrial gene expressioncarbohydrate derivative metabolic processother biological processall cellular componentnuclear chromosomeextracellular regionextracellular spacecell wallnucleusnuclear envelopenucleoplasmchromosomenucleolusmitochondrionlysosomeendosomevacuoleperoxisomeendoplasmic reticulumgolgi apparatuslipid dropletmicrotubule organizing centercytosolribosomecytoskeletonplasma membraneciliumplastidthylakoidexternal encapsulating structureextracellular matrixcytoplasmic vesicleorganelleother cellular component
Cell color indicative of number of GO terms
AspectTerm
Cellular Componenthost cell
Cellular Componenthost cell cytoplasm
Cellular ComponentT=4 icosahedral viral capsid
Molecular FunctionDNA binding
Molecular FunctionRNA binding
Molecular Functionstructural molecule activity
Biological Processmicrotubule-dependent intracellular transport of viral material towards nucleus
Biological Processsymbiont entry into host cell
Biological Processviral penetration into host nucleus

Keywords

Names & Taxonomy

Protein names

  • Recommended name
    Capsid protein
  • Alternative names
    • Core antigen
    • Core protein
    • HBcAg
    • p21.5

Gene names

    • Name
      C

Organism names

Accessions

  • Primary accession
    Q9QMI2

Proteomes

Subcellular Location

PTM/Processing

Features

Showing features for chain, modified residue.

TypeIDPosition(s)Description
ChainPRO_00003243701-183Capsid protein
Modified residue155Phosphoserine; by host
Modified residue162Phosphoserine; by host
Modified residue170Phosphoserine; by host

Post-translational modification

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.

Keywords

Interaction

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.

Structure

Family & Domains

Features

Showing features for region, compositional bias, repeat, motif.

TypeIDPosition(s)Description
Region136-183Disordered
Compositional bias152-173Basic residues
Repeat155-1611; half-length
Region155-1773 X 8 AA repeats of S-P-R-R-R-[PR]-S-Q
Motif158-175Bipartite nuclear localization signal
Repeat162-1692
Repeat170-1773
Region177-183RNA binding

Sequence similarities

Belongs to the orthohepadnavirus core antigen family.

Keywords

Family and domain databases

Sequence & Isoform

Align isoforms (2)
  • Sequence status
    Complete

This entry describes 2 isoforms produced by Alternative initiation.

Q9QMI2-1

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
    Capsid protein
  • See also
    sequence in UniParc or sequence clusters in UniRef
  • Length
    183
  • Mass (Da)
    21,058
  • Last updated
    2000-05-01 v1
  • Checksum
    421A92A5A8E24270
MDIDPYKEFGATVELLSFLPSDFFPSVRDLLDTAAALYRDALESPEHCSPHHTALRQAILCWGDLITLSTWVGTNLEDPASRDLVVSYVNSNMGLKFRQLLWFHISCLTFGRETVLEYLVSFGVWIRTPPAYRPPNAPILSTLPETTVVRRRGRSPRRRTPSPRRRRSQSPRRRRSQSRESQC

P0C6I0-1

The sequence of this isoform can be found in the external entry linked below. Isoforms of the same protein are often annotated in two different entries if their sequences differ significantly.

View isoform
  • Name
    External core antigen
  • See also
    sequence in UniParc or sequence clusters in UniRef

Features

Showing features for compositional bias.

TypeIDPosition(s)Description
Compositional bias152-173Basic residues

Keywords

Sequence databases

Nucleotide SequenceProtein SequenceMolecule TypeStatus
AB033558
EMBL· GenBank· DDBJ
BAA85372.1
EMBL· GenBank· DDBJ
Genomic DNA

Similar Proteins

Disclaimer

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