Table 1.
Details on the SARS-CoV-2 proteins and their roles.
| Proteins | Roles |
|---|---|
| Nsp1 | inhibits host innate immune response; increases proinflammatory chemokine production |
| Nsp2 | acts as an Nsp3 adaptor |
| PLpro/Nsp3 | interacts with Nsp4 and Nsp6 and forms a complex; strips ubiquitin and blocks the host innate immune response |
| Nsp4 | interacts with Nsp3 and Nsp6; anchors the replication complex to double-membrane vesicles |
| Nsp5/3CLPro | causes cleavage of viral polyproteins, thus decreasing individual Nsps |
| Nsp6 | interacts with Nsp3 and Nsp4; limits the expansion of autophagosome and lysosomal viral degradation |
| Nsp7/primase | forms the primase complex as part of the replication complex (Nsp7/8/12); can perform both de novo initiation and primer extension |
| Nsp8/primase | interacts with Nsp7 and the Nsp7/Nsp8 complex, thus forming the RNA transcriptase-replicase complex; the Nsp7/Nsp8 complex stabilizes the Nsp12 regions involved in RNA binding |
| Nsp9/RNA-binding protein | interacts with the replication complex (Nsp7/8/12) |
| Nsp10 | interacts with Nsp16, which is required for replication; stimulates Nsp16 methyltransferase activity; interacts with Nsp14, thus facilitating exoribonuclease and methyltransferase activities |
| Nsp12 (RNA-dependent RNA polymerase) | interacts with Nsp7 and Nsp8, thus forming an RNA transcriptase-replicase complex |
| Nsp13/NTPase/helicase | initiates the capping of viral mRNA (along with Nsp14 and Nsp16) and installs the cap structure onto viral mRNA |
| methyltransferase/exoribonuclease/NSP14 | repairs mutation errors during replication; involved in viral mRNA capping |
| uridylate-specific endoribonuclease/NSP15 | required for viral RNA synthesis |
| 2′-O-methyltransferase/NSP16 | forms a complex with NSP10; involved in the S-adenosyl-L-methionine cap methylation of mRNA |
| NSP11 | short peptide with unknown function |
| spike (S) protein | binds the ACE2 receptor on host cells and initiates viral fusion with the host cell membrane |
| envelope (E) protein | involved in viral assembly |
| membrane (M) protein | involved in viral assembly |
| nucleocapsid (N) protein | binds viral RNA |
| ORF3a | involved in the trafficking of S-protein and apoptosis |
| ORF3b | inhibits the activities of interferons |
| ORF6 | interferon I antagonist that binds karyopherins and decreases the interferon/antiviral response |
| ORF7a | involved in virus-induced apoptosis; inhibits CD317, which prevents the release of CoVs |
| ORF7b | unknown function |
| ORF8 | unknown function |
| ORF9b | involved in the degradation of signalosomes; limits host cell interferon responses |
| ORF9c | unknown |
| ORF10 | unknown |