Table 1.
Summary of SARS proteins.
| Protein | Protein size (amino acids) | ORF (location in genome sequence) | Putative functional domain(s) | Structure available? |
|---|---|---|---|---|
|
Structural proteins | ||||
| Spike (S) protein | 1255 | ORF2 (21492–25259) | Yes (S protein fusion core) | |
| Envelope (E) protein | 76 | ORF4 (26117–26347) | No | |
| Membrane (M) protein | 221 | ORF5 (26398–27063) | No | |
| Nucleocapsid (N) protein | 422 | ORF9a (28120–29388) | Yes (N-terminal RNA-binding domain) | |
|
Non-structural proteins (Nsps) | ||||
| Nsp1 | 180 | ORF1a (265–804) | No | |
| Nsp2 | 638 | ORF1a (805–2718) | No | |
| Nsp3 | 1922 | ORF1a (2719–8484) | Ac, X, PL2pro, Y (TM1), ADRP | No |
| Nsp4 | 500 | ORF1a (8485–9984) | TM2 | No |
| Nsp5 | 306 | ORF1a (9985–10902) | Mpro | Yes |
| Nsp6 | 290 | ORF1a (10903–11772) | TM3 | No |
| Nsp7 | 83 | ORF1a (11773–12021) | Yesa | |
| Nsp8 | 198 | ORF1a (12022–12615) | Yesa | |
| Nsp9 | 113 | ORF1a (12616–12954) | ssRNA binding | Yes |
| Nsp10 | 139 | ORF1a (12955–13371) | GFL | No |
| Nsp11 | 13 | ORF1a (13372–13410) | No | |
| Nsp12 | 932 | ORF1b (13398–16166) | RdRp | No |
| Nsp13 | 601 | ORF1b (16167–17969) | ZD, NTPase, HEL1 | No |
| Nsp14 | 527 | ORF1b (17970–19550) | Exonuclease (ExoN homologue) | No |
| Nsp15 | 346 | ORF1b (19551–20588) | NTD, endoribonuclease (XendoU homologue) | No |
| Nsp16 | 298 | ORF1b (20589–21482) | 2′-O-MT | No |
|
Accessory proteins | ||||
| Orf3a | 274 | ORF3a (25268–26092) | No | |
| Orf3b | 154 | ORF3b (25689–26153) | No | |
| Orf6 | 63 | ORF6 (26913–27265) | No | |
| Orf7a | 122 | ORF7a (27273–27641) | Ig like | Yes (luminal domain) |
| Orf7b | 44 | ORF7b (27638–27772) | No | |
| Orf8a | 39 | ORF8a (27779–27898) | No | |
| Orf8b | 84 | ORF8b (27864–28118) | No | |
| Orf9b | 98 | ORF9b (28130–28426) | No | |
a
Structure has been deposited in the PDB, but has not been published. Ac, acidic domain; ADRP, adenosine diphosphate-ribose 1′-phosphatase; ExoN, 3′-5′ exonuclease; GFL, growth-factor-like domain; HEL1, superfamily 1 helicase; Mpro, main (or 3C-like cysteine) protease; NTD, nidovirus conserved domain; NTPase, nucleoside triphosphatase; 2′-O-MT, S-adenosylmethionine-dependent ribose 2′-O-methyltransferase; PL2pro, papain-like protease 2; RdRp, RNA-dependent RNA polymerase; TM, transmembrane domain; X, Y, domains with unknown or hypothetical function; ZD, putative zinc-binding domain.