ID   CAPSD_WHV4              Reviewed;         188 AA.
AC   P69710; P03152;
DT   21-JUL-1986, integrated into UniProtKB/Swiss-Prot.
DT   21-JUL-1986, sequence version 1.
DT   02-SEP-2026, entry version 89.
DE   RecName: Full=Capsid protein {ECO:0000255|HAMAP-Rule:MF_04076};
DE   AltName: Full=Core antigen {ECO:0000255|HAMAP-Rule:MF_04076};
DE   AltName: Full=Core protein {ECO:0000255|HAMAP-Rule:MF_04076};
DE   AltName: Full=HBcAg {ECO:0000255|HAMAP-Rule:MF_04076};
DE   AltName: Full=p21.5 {ECO:0000255|HAMAP-Rule:MF_04076};
GN   Name=C {ECO:0000255|HAMAP-Rule:MF_04076};
OS   Woodchuck hepatitis B virus (isolate 7) (WHV).
OC   Viruses; Riboviria; Pararnavirae; Artverviricota; Revtraviricetes;
OC   Blubervirales; Hepadnaviridae; Orthohepadnavirus;
OC   Orthohepadnavirus marmotae; Woodchuck hepatitis virus.
OX   NCBI_TaxID=10432;
OH   NCBI_TaxID=9995; Marmota monax (Woodchuck).
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=3336938; DOI=10.1016/0042-6822(88)90389-3;
RA   Cohen J.I., Miller R.H., Rosenblum B., Denniston K., Gerin J.L.,
RA   Purcell R.H.;
RT   "Sequence comparison of woodchuck hepatitis virus replicative forms shows
RT   conservation of the genome.";
RL   Virology 162:12-20(1988).
CC   -!- FUNCTION: Self assembles to form an icosahedral capsid. Most capsids
CC       appear to be large particles with an icosahedral symmetry of T=4 and
CC       consist of 240 copies of capsid protein, though a fraction forms
CC       smaller T=3 particles consisting of 180 capsid proteins. Entering
CC       capsids are transported along microtubules to the nucleus.
CC       Phosphorylation of the capsid is thought to induce exposure of nuclear
CC       localization signal in the C-terminal portion of the capsid protein
CC       that allows binding to the nuclear pore complex via the importin
CC       (karyopherin-) alpha and beta. Capsids are imported in intact form
CC       through the nuclear pore into the nuclear basket, where it probably
CC       binds NUP153. Only capsids that contain the mature viral genome can
CC       release the viral DNA and capsid protein into the nucleoplasm. Immature
CC       capsids get stuck in the basket. Capsids encapsulate the pre-genomic
CC       RNA and the P protein. Pre-genomic RNA is reverse-transcribed into DNA
CC       while the capsid is still in the cytoplasm. The capsid can then either
CC       be directed to the nucleus, providing more genomes for transcription,
CC       or bud through the endoplasmic reticulum to provide new virions.
CC       {ECO:0000255|HAMAP-Rule:MF_04076}.
CC   -!- SUBUNIT: Homodimerizes, then multimerizes. Interacts with cytosol
CC       exposed regions of viral L glycoprotein present in the reticulum-to-
CC       Golgi compartment. Interacts with human FLNB. Phosphorylated form
CC       interacts with host importin alpha; this interaction depends on the
CC       exposure of the NLS, which itself depends upon genome maturation and/or
CC       phosphorylation of the capsid protein. Interacts with host NUP153.
CC       {ECO:0000255|HAMAP-Rule:MF_04076}.
CC   -!- SUBCELLULAR LOCATION: Virion {ECO:0000255|HAMAP-Rule:MF_04076}. Host
CC       cytoplasm {ECO:0000255|HAMAP-Rule:MF_04076}.
CC   -!- ALTERNATIVE PRODUCTS:
CC       Event=Alternative initiation; Named isoforms=2;
CC       Name=Capsid protein;
CC         IsoId=P69710-1; Sequence=Displayed;
CC       Name=External core antigen;
CC         IsoId=P0C6J5-1; Sequence=External;
CC   -!- PTM: Phosphorylated by host SRPK1, SRPK2, and maybe protein kinase C or
CC       GAPDH. Phosphorylation is critical for pregenomic RNA packaging.
CC       Protein kinase C phosphorylation is stimulated by HBx protein and may
CC       play a role in transport of the viral genome to the nucleus at the late
CC       step during the viral replication cycle. {ECO:0000255|HAMAP-
CC       Rule:MF_04076}.
CC   -!- SIMILARITY: Belongs to the orthohepadnavirus core antigen family.
CC       {ECO:0000255|HAMAP-Rule:MF_04076}.
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DR   EMBL; M18752; AAA46769.1; -; Genomic_DNA.
DR   PIR; C32397; NKVLC.
DR   RefSeq; NP_671816.1; NC_004107.1.
DR   AlphaFoldDB; P69710; -.
DR   SMR; P69710; -.
DR   GeneID; 2546420; -.
DR   KEGG; vg:2546420; -.
DR   Proteomes; UP000008598; Segment.
DR   GO; GO:0043657; C:host cell; IEA:GOC.
DR   GO; GO:0030430; C:host cell cytoplasm; IEA:UniProtKB-SubCell.
DR   GO; GO:0039619; C:T=4 icosahedral viral capsid; IEA:UniProtKB-UniRule.
DR   GO; GO:0003677; F:DNA binding; IEA:UniProtKB-UniRule.
DR   GO; GO:0003723; F:RNA binding; IEA:UniProtKB-UniRule.
DR   GO; GO:0005198; F:structural molecule activity; IEA:UniProtKB-UniRule.
DR   GO; GO:0075521; P:microtubule-dependent intracellular transport of viral material towards nucleus; IEA:UniProtKB-UniRule.
DR   GO; GO:0046718; P:symbiont entry into host cell; IEA:UniProtKB-UniRule.
DR   GO; GO:0075732; P:viral penetration into host nucleus; IEA:UniProtKB-UniRule.
DR   Gene3D; 1.10.4090.10; Viral capsid, core domain supefamily, Hepatitis B virus; 1.
DR   HAMAP; MF_04076; HBV_HBEAG; 1.
DR   InterPro; IPR002006; Hepatitis_core.
DR   InterPro; IPR036459; Viral_capsid_core_dom_sf_HBV.
DR   Pfam; PF00906; Hepatitis_core; 3.
DR   SUPFAM; SSF47852; Hepatitis B viral capsid (hbcag); 1.
PE   3: Inferred from homology;
KW   Alternative initiation; Capsid protein;
KW   Cytoplasmic inwards viral transport; DNA-binding; Host cytoplasm;
KW   Host-virus interaction; Microtubular inwards viral transport;
KW   Phosphoprotein; Reference proteome; Repeat; RNA-binding;
KW   T=4 icosahedral capsid protein; Viral penetration into host nucleus;
KW   Virion; Virus entry into host cell.
FT   CHAIN           1..188
FT                   /note="Capsid protein"
FT                   /id="PRO_0000222323"
FT   REPEAT          160..166
FT                   /note="1; half-length"
FT   REPEAT          167..174
FT                   /note="2"
FT   REPEAT          175..182
FT                   /note="3"
FT   REGION          150..188
FT                   /note="Disordered"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   REGION          160..182
FT                   /note="3 X 8 AA repeats of S-P-R-R-R-[PR]-S-Q"
FT   REGION          182..188
FT                   /note="RNA binding"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_04076"
FT   MOTIF           163..180
FT                   /note="Bipartite nuclear localization signal"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_04076"
FT   COMPBIAS        150..181
FT                   /note="Basic residues"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   MOD_RES         160
FT                   /note="Phosphoserine; by host"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_04076"
FT   MOD_RES         167
FT                   /note="Phosphoserine; by host"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_04076"
FT   MOD_RES         175
FT                   /note="Phosphoserine; by host"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_04076"
SQ   SEQUENCE   188 AA;  21694 MW;  1F4454D0A7B7CE42 CRC64;
     MDIDPYKEFG SSYQLLNFLP LDFFPDLNAL VDTATALYEE ELTGREHCSP HHTAIRQALV
     CWDELTKLIA WMSSNITSEQ VRTIIVNHVN DTWGLKVRQS LWFHLSCLTF GQHTVQEFLV
     SFGVWIRTPA PYRPPNAPIL STLPEHTVIR RRGGARASRS PRRRTPSPRR RRSQSPRRRR
     SQSPSANC
//