Recombinant Hepatitis B Virus Core Antigen protein

Specifications

Form

Liquid

General info

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.

Sequence similarities

Belongs to the orthohepadnavirus core antigen family.

Post-translational modifications

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.