Table 1.
Structural protein | Function | Refs |
---|---|---|
Spike protein | Viral entry – binds to ACE2 receptor and heparan sulfate | [25,94] |
Envelope protein | Virion structure | [3] |
Membrane protein | Virion structure | [3] |
Nucleocapsid | Houses genome, interferes with host translation and cell cycle, regulates cytoskeleton organization | [30,99] |
Nonstructural protein | ||
NSP1 | Inhibits host translation and the IFN response | [33,35] |
NSP2 | Disrupts cell cycle progression and apoptosis, possibly regulates actin assembly | [37,38] |
NSP3 | Facilitates transcription of the viral genome, arrests cell cycle in the G0/G1 phase, contains PLpro which antagonizes host immune responses and frees NSPs 1–3 | [40,95,97] |
NSP4 | Participates in membrane rearrangement | [45] |
NSP5 | Contains the main protease, regulates epigenetic and gene expression, influences ER and mitochondrial functioning | [2,48,50] |
NSP6 | Restricts host autophagosome expansion | [52] |
NSP7 | Complexes with NSP8 to form RNA primase | [53] |
NSP8 | Complexes with NSP7 to form RNA primase | [53] |
NSP9 | RNA-binding phosphatase | [56] |
NSP10 | Activation cofactor for NSP14 and NSP16 | [60,61] |
NSP11 | Unknown | [98] |
NSP12 | RdRp – complexes with NSP7 and NSP8 to replicate viral genome | [65] |
NSP13 | Helicase | [69,70] |
NSP14 | 3′-5′-exoribonuclease, interacts with replication-transcription complex | [74] |
NSP15 | Endoribonuclease, IFN inhibitor, and modifies host cell cycle progression | [76,79] |
ORF3a | Ion channel protein, influences cytokine responses | [81,82] |
ORF6 | Inhibits antiviral IFN response | [84] |
ORF7a | Suppresses STAT1 phosphorylation, inhibits type 1 IFN response | [8] |
ORF7b | Suppresses STAT1 and STAT2 phosphorylation, inhibits type 1 IFN response | [8] |
ORF8 | Inhibits antiviral IFN response, immune evasion virulence factor | [78] |
The proteins are divided between structural and nonstructural types. The functions and associated references are provided for each protein.