N
Function
Packages the positive strand viral genome RNA into a helical ribonucleocapsid (RNP) and plays a fundamental role during virion assembly through its interactions with the viral genome and membrane protein M. Plays an important role in enhancing the efficiency of subgenomic viral RNA transcription as well as viral replication (PubMed:17210170). May modulate transforming growth factor-beta signaling by binding host SMAD3 (PubMed:18055455).
Post-translational modifications
Proteolytically cleaved by host CASP6. The cleavage leads to two fragments and facilitates viral replication by inhibiting host IFN signaling. The two fragments may interact with IRF3 inhibiting its nuclear translocation after activation and reduce the expression of IFNB and IFN-stimulated genes.
ADP-ribosylated. The ADP-ribosylation is retained in the virion during infection.
Phosphorylated on serine and threonine residues (PubMed:19106108). Phosphorylated by host GSK3A and GSK3B. Phosphorylation allows recruitment of host RNA helicase DDX1 which facilitates template readthrough and enables longer subgenomic mRNA synthesis. This promotes the solubility of homodimers that would otherwise aggregate (PubMed:32974389). Host phosphatase would dephosphorylate the protein during assembly at M bound membranes (PubMed:32974389).
Sequence Similarities
Belongs to the betacoronavirus nucleocapsid protein family.
Cellular localization
- Virion
- Host endoplasmic reticulum-Golgi intermediate compartment
- Host Golgi apparatus
- Host cytoplasm
- Host perinuclear region
- Host nucleus
- Located inside the virion, complexed with the viral RNA. Probably associates with ER-derived membranes where it participates in viral RNA synthesis and virus budding.
Alternative names
9a, N, Nucleoprotein, Nucleocapsid protein, NC, Protein N