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 (PubMed:33264373). Plays an important role in enhancing the efficiency of subgenomic viral RNA transcription as well as viral replication. Attenuates the stress granules formation by reducing host G3BP1 access to host mRNAs under stress conditions (PubMed:34901782, PubMed:36534661).FUNCTION May block host chemokine function in vivo, facilitating viral replication and transmission (PubMed:35921414). Acts by being secreted into the extracellular space where it competes to host chemokines for binding to host glycosaminoglycans (GAG) (PubMed:35921414).FUNCTION May induce inflammasome responses in cultured cells and mice. Acts by interacting with host NLRP3 to facilitate inflammasome assembly, which induces cytokine release that may play a role in COVID lung injury. Disrupts the association betwen NLRP3 and ABHD8, enhancing NLRP3 stability and leading to increased inflammasome activation (PubMed:39225180).SUBUNIT Homodimer, homotetramer, homooligomer with RNA (PubMed:32654247). Both monomeric and oligomeric forms interact with RNA. Interacts with protein M (By similarity). Interacts with protein E (By similarity). Interacts with NSP3; this interaction serves to tether the genome to the newly translated replicase-transcriptase complex at a very early stage of infection (PubMed:35044811). Interacts with host NLRP3 and ABHD8; these interactions disrupt the association between NLRP3 and ABHD8, increasing NLRP3 stability, ultimately leading to increased inflammasome activation (PubMed:34341353, PubMed:39225180). Interacts with host G3BP1; the interaction is enhanced by host HDAC6 which deacetylates the viral N protein and promotes N protein association with G3BP1, disrupting stress granule formation and facilitating viral replication (PubMed:39135075).INTERACTION Probably associates with ER-derived membranes where it participates in viral RNA synthesis and virus budding. When located inside the virion, complexed with the viral RNA. Can be secreted by unconventional protein secretion (UPS) (PubMed:35921414). When secreted, can bind to host glycosaminoglycans on infected and non infected cells (PubMed:35921414). Found in host cytoplasmic stress granules (PubMed:34901782).PTM ADP-ribosylated. The ADP-ribosylation is retained in the virion during infection.PTM Phosphorylated on serine residues by host GSK3A and GSK3B (PubMed:34593624, PubMed:35728038). 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).PTM 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.PTM Acetylated (PubMed:39135075). Deacetylated by host HDAC6 which promotes association of the viral N protein with human G3BP1, disrupting cellular stress granule formation and facilitating viral replication (PubMed:39135075).POLYMORPHISM Variant Alpha/B.1.1.7 belongs to a lineage isolated first in United Kingdom (December 2020). It is also called Variant of Concern (VOC) 202012/01, Variant Under Investigation (VUI) 202012/01, 501Y.V1 or 20B/501Y.V1.POLYMORPHISM Variant Omicron/BA.1 and BA.2 belong to a lineage first isolated in South Africa (November 2021).POLYMORPHISM Variant Omicron/BQ.1.1 belongs to a lineage first isolated in Nigeria (November 2022).POLYMORPHISM Variant Omicron/XBB.1.5 belongs to a lineage first isolated in United States (November 2022). It is the result of recombination between omicron BJ.1 and BM.1.1. Moreover XBB.1.5 do not express ORF8.SIMILARITY Belongs to the betacoronavirus nucleocapsid protein family.
recommendedName: fullName evidence="2"Nucleoprotein shortName: N alternativeName: fullName evidence="2"Nucleocapsid protein shortName evidence="2"NC shortName evidence="2"Protein N