TABLE 1.
S1-S2 junction sequences of coronavirus S proteins and their predicted and observed furin cleavage
| Group | Virus straind | Sequencea | Predictionb | Confirmation of protein cleavagec | Reference(s) |
|---|---|---|---|---|---|
| 1 | FCoV UCD | NHTHSRRSRRSTLTSV | + (0.835) | + | This study; 33, 46 |
| 1 | FCoV UCD1 | NHTHSRRSRGSTSTSV | − (0.383) | − | This study; 31, 32 |
| 1 | FCoV UCD8 | NHTQPRRSRRSTPNSV | + (0.819) | ND | 24, 31 |
| 1 | CCoV Elmö | HTHTVRRARRAVQTGT | + (0.787) | ND | 35 |
| 1 | FCoV 1146 | NGALVFINTVTHSDGD | − (0) | − | 6, 45 |
| 1 | HCoV NL63 | DGSLIPVRPRNSSDNG | − (0.105) | ND | 44 |
| 2a | MHV A59 | DYSKSRRAHRSVSTGY | + (0.802) | + | 15, 29 |
| 2a | MHV/BHK | DYSKSRRAHRLGSTGY | − (0.359) | − | 8, 39 |
| 2a | MHV-2 | NYSTSRHARSSVSTGY | − (0.207) | − | 36, 52 |
| 2a | HCoV OC43 BE03 | DYSKNRRSRRAITTGY | + (0.751) | ND | 48 |
| 2a | HCoV OC43 ATCC | DYSKNRRSRGAITTGY | + (0.551) | − | 21, 27 |
| 2a | BCV Mebus | DYSTKRRSRRAITTGY | + (0.774) | + | 1 |
| 2b | SARS-CoV | SYHTVSLLRSTSQKSI | − (0.123) | − | 14, 23, 42, 51 |
| 3 | IBV Bdtt | ITNGTRRFRRSITENV | + (0.833) | + | 2, 5 |
Basic amino acids are in bold; residues immediately downstream of the (putative) cleavage site are italicized; residues mutated, presumably as a result of cell culture adaptation, are underlined.
+ and − indicate whether a furin-specific cleavage site is or is not predicted (11) between the S1 and S2 domains of the spike protein, respectively. The numbers in parentheses indicate the probability scores of furin cleavage; 0.5 is used as the cutoff value.
+ and − indicate whether or not the spike protein cleavage during virus assembly and release has been experimentally confirmed, respectively. ND (not determined) indicates the lack of experimental data.
MHV-2 and SARS-CoV, but not HCoV NL63 or MHV A59, require endosomal proteolysis by cathepsins for their entry. BCV, bovine coronavirus; IBV, infectious bronchitis virus.