Q76R61 (CAPSD_HBVCJ) Reviewed, UniProtKB/Swiss-Prot

Names and origin

Protein names

Recommended name:
Capsid protein

Alternative name(s):
Core antigen
Core protein
HBcAg
p21.5

Gene names

Name:

C

Organism

Hepatitis B virus genotype C subtype ayr (isolate Human/Japan/Okamoto/-) (HBV-C)

Taxonomic identifier

928302 [NCBI]

Taxonomic lineage

Viruses › Retro-transcribing viruses › Hepadnaviridae › Orthohepadnavirus

Virus host

Pan troglodytes (Chimpanzee) [TaxID: 9598]
Homo sapiens (Human) [TaxID: 9606]

Protein attributes

Sequence length	183 AA.
Sequence status	Complete.
Protein existence	Evidence at protein level

General annotation (Comments)

Function	Self assembles to form an icosahedral capsid. Most capsid appear to be large particles with a 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 capsid 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 stucked 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 genome for transcription, or bud through the endoplasmic reticulum to provide new virions. Ref.3 Ref.4 Ref.5 Encapsidates hepatitis delta genome By similarity. Ref.3 Ref.4 Ref.5
Subunit structure	Homodimerizes, then multimerizes. Interacts with cytosol exposed regions of viral L glycoprotein present in the reticulum-to-Golgi compartment. Interacts with human FLNB By similarity. 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. Ref.2 Ref.5
Subcellular location	Capsid protein: Virion. Host cytoplasm By similarity.
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 viral replication cycle By similarity.
Sequence similarities	Belongs to the orthohepadnavirus core antigen family.

Ontologies

Keywords
Biological process	Cytoplasmic active transport of viral material Host-virus interaction Initiation of viral infection Microtubule-dependent active transport of viral material Viral penetration into host nucleus
Cellular component	Host cytoplasm Virion
Coding sequence diversity	Alternative initiation
Domain	Repeat
Ligand	DNA-binding RNA-binding
Molecular function	Capsid protein T=4 icosahedral capsid protein
PTM	Phosphoprotein
Technical term	Complete proteome Reference proteome
Gene Ontology (GO)
Biological process	interspecies interaction between organisms Inferred from electronic annotation. Source: UniProtKB-KW pathogenesis Inferred from electronic annotation. Source: InterPro
Cellular component	host cell cytoplasm Inferred from electronic annotation. Source: UniProtKB-SubCell viral capsid Inferred from electronic annotation. Source: UniProtKB-KW
Molecular function	DNA binding Inferred from electronic annotation. Source: UniProtKB-KW RNA binding Inferred from electronic annotation. Source: UniProtKB-KW structural molecule activity Inferred from electronic annotation. Source: InterPro
Complete GO annotation...

Alternative products

This entry describes 2 isoforms produced by alternative initiation. [Align] [Select]

Isoform Capsid protein (identifier: Q76R61-1)

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.

Isoform External core antigen (identifier: P0C767-1)

The sequence of this isoform can be found in the external entry P0C767.
Isoforms of the same protein are often annotated in two different entries if their sequences differ significantly.

Sequence annotation (Features)

	Feature key	Position(s)	Length	Description	Graphical view	Feature identifier
Molecule processing
	Chain	1 – 183	183	Capsid protein		PRO_0000390308
Regions
	Repeat	155 – 161	7	1; half-length
	Repeat	162 – 169	8	2
	Repeat	170 – 177	8	3
	Region	155 – 177	23	3 X 8 AA repeats of S-P-R-R-R-[PR]-S-Q
	Region	177 – 183	7	RNA binding
	Motif	158 – 175	18	Bipartite nuclear localization signal Potential
	Compositional bias	164 – 167	4	Poly-Arg
	Compositional bias	172 – 175	4	Poly-Arg
Amino acid modifications
	Modified residue	155	1	Phosphoserine; by host By similarity
	Modified residue	162	1	Phosphoserine; by host By similarity
	Modified residue	170	1	Phosphoserine; by host By similarity

Sequences

	Sequence		Length	Mass (Da)
	Isoform Capsid protein [UniParc]. Last modified July 7, 2009. Version 1. Checksum: ED2DA1DB07FB596D	FASTA	183	21,095
	10 20 30 40 50 60 MDIDPYKEFG ASVELLSFLP SDFFPSIRDL LDTASALYRE ALESPEHCSP HHTALRQAIL 70 80 90 100 110 120 CWGELMNLAT WVGSNLEDPA SRELVVSYVN VNMGLKIRQL LWFHISCLTF GRETVLEYLV 130 140 150 160 170 180 SFGVWIRTPP AYRPPNAPIL STLPETTVVR RRGRSPRRRT PSPRRRRSQS PRRRRSQSRE SQC
	Isoform External core antigen [UniParc]. See P0C767.		–	–

References

[1]	"Nucleotide sequence of a cloned hepatitis B virus genome, subtype ayr: comparison with genomes of the other three subtypes." Okamoto H., Imai M., Shimozaki M., Hoshi Y., Iizuka H., Gotanda T., Tsuda F., Miyakawa Y., Mayumi M. J. Gen. Virol. 67:2305-2314(1986) [PubMed: 3783127] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA].
[2]	"Phosphorylation-dependent binding of hepatitis B virus core particles to the nuclear pore complex." Kann M., Sodeik B., Vlachou A., Gerlich W.H., Helenius A. J. Cell Biol. 145:45-55(1999) [PubMed: 10189367] [Abstract] Cited for: NUCLEAR LOCALIZATION SIGNAL, INTERACTION WITH HOST IMPORTIN ALPHA.
[3]	"Nuclear import of hepatitis B virus capsids and release of the viral genome." Rabe B., Vlachou A., Pante N., Helenius A., Kann M. Proc. Natl. Acad. Sci. U.S.A. 100:9849-9854(2003) [PubMed: 12909718] [Abstract] Cited for: FUNCTION.
[4]	"Itinerary of hepatitis B viruses: delineation of restriction points critical for infectious entry." Funk A., Mhamdi M., Lin L., Will H., Sirma H. J. Virol. 78:8289-8300(2004) [PubMed: 15254201] [Abstract] Cited for: FUNCTION.
[5]	"Nucleoporin 153 arrests the nuclear import of hepatitis B virus capsids in the nuclear basket." Schmitz A., Schwarz A., Foss M., Zhou L., Rabe B., Hoellenriegel J., Stoeber M., Pante N., Kann M. PLoS Pathog. 6:E1000741-E1000741(2010) [PubMed: 20126445] [Abstract] Cited for: FUNCTION, INTERACTION WITH RAT NUP153.

Cross-references

Sequence databases
EMBL GenBank DDBJ	X04615 Genomic DNA. Translation: CAA28289.1.
RefSeq	NP_647607.1. NC_003977.1.
3D structure databases
ProteinModelPortal	Q76R61.
ModBase	Search...
Protocols and materials databases
StructuralBiologyKnowledgebase	Search...
Genome annotation databases
GeneID	944568.
Family and domain databases
InterPro	IPR002006. Viral_capsid_core_Hepatitis. [Graphical view]
Pfam	PF00906. Hepatitis_core. 1 hit. [Graphical view]
SUPFAM	SSF47852. Viral_capsid_core_Hepatitis. 1 hit.
ProtoNet	Search...

Entry information

Entry name

CAPSD_HBVCJ

Accession

Primary (citable) accession number: Q76R61

Entry history

Integrated into UniProtKB/Swiss-Prot:	December 15, 2009
Last sequence update:	July 7, 2009
Last modified:	September 21, 2011
This is version 21 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation program

Viral Protein Annotation Program