Table 1.
COVID-19 Structural, Nonstructural, and Accessory Proteins
| Replication Phase | Host Factor | Virus Factor | Function |
|---|---|---|---|
| Binding and entry | ACE2 | Spike glycoprotein (S) | Cellular receptor |
| Viral transcription/replication, ribosome frameshift | Replicase polyprotein 1a (R1a) | ||
| Viral transcription/replication, ribosome frameshift | Replicase polyprotein 1ab (R1ab) | ||
| Protein 3a | Independent budding | Induction of apoptosis | |
| Protein 3b | Inhibition of type I interferons, induction of apoptosis | ||
| Envelope small membrane protein (E) | Independent budding | ||
| Membrane protein (M) | Virion morphogenesis | ||
| Nonstructural protein 6 (NS6) | Inhibition of type I interferons, alteration in cellular DNA synthesis | ||
| Nonstructural protein 7a (Ns7a) | Activate inflammation (MAPK-8) and NF-κB pathways | ||
| Ns7b | Unknown | ||
| Ns8a | Induction of apoptosis, alteration in cellular DNA synthesis | ||
| Nucleoprotein (N) | Viral genome packaging | ||
| Ns14 | Exonuclease and repair activity | ||
| Ns9b | Unknown | ||
| Ns10 | Unknown | ||
| IFITM (interferon-induced transmembrane) | Inhibits cell entry | ||
| TMPRSS2 (transmembrane protease serine 2) | Cleaves and activates S protein | ||
| Furin | Cleaves and activates S protein | ||
| Genome replication and transcription | GSK3 (glycogen synthase kinase 3) | Phosphorylates N protein and facilitates viral replication | |
| Translation of structural proteins | N-linked glycosylation enzymes in Golgi | Modifies S and M protein; N-linked glycosylation of the S protein facilitates lectin-mediated virion attachment and constitutes some neutralizing epitopes | |
| Endoplasmic reticulum chaperones | Proper folding and maturation of protein |
Note: ACE2 = angiotensin-converting enzyme 2; COVID-19 = coronavirus disease 2019.