Id |
Subject |
Object |
Predicate |
Lexical cue |
T94 |
0-14 |
Sentence |
denotes |
S Glycoprotein |
T95 |
15-101 |
Sentence |
denotes |
Coronavirus S protein is a large, multifunctional class I viral transmembrane protein. |
T96 |
102-268 |
Sentence |
denotes |
The size of this abundant S protein varies from 1,160 amino acids (IBV, infectious bronchitis virus, in poultry) to 1,400 amino acids (FCoV, feline coronavirus) (43). |
T97 |
269-364 |
Sentence |
denotes |
It lies in a trimer on the virion surface, giving the virion a corona or crown-like appearance. |
T98 |
365-518 |
Sentence |
denotes |
Functionally it is required for the entry of the infectious virion particles into the cell through interaction with various host cellular receptors (44). |
T99 |
519-621 |
Sentence |
denotes |
Furthermore, it acts as a critical factor for tissue tropism and the determination of host range (45). |
T100 |
622-740 |
Sentence |
denotes |
Notably, S protein is one of the vital immunodominant proteins of CoVs capable of inducing host immune responses (45). |
T101 |
741-857 |
Sentence |
denotes |
The ectodomains in all CoVs S proteins have similar domain organizations, divided into two subunits, S1 and S2 (43). |
T102 |
858-955 |
Sentence |
denotes |
The first one, S1, helps in host receptor binding, while the second one, S2, accounts for fusion. |
T103 |
956-1076 |
Sentence |
denotes |
The former (S1) is further divided into two subdomains, namely, the N-terminal domain (NTD) and C-terminal domain (CTD). |
T104 |
1077-1192 |
Sentence |
denotes |
Both of these subdomains act as receptor-binding domains, interacting efficiently with various host receptors (45). |
T105 |
1193-1246 |
Sentence |
denotes |
The S1 CTD contains the receptor-binding motif (RBM). |
T106 |
1247-1350 |
Sentence |
denotes |
In each coronavirus spike protein, the trimeric S1 locates itself on top of the trimeric S2 stalk (45). |
T107 |
1351-1492 |
Sentence |
denotes |
Recently, structural analyses of the S proteins of COVID-19 have revealed 27 amino acid substitutions within a 1,273-amino-acid stretch (16). |
T108 |
1493-1633 |
Sentence |
denotes |
Six substitutions are located in the RBD (amino acids 357 to 528), while four substitutions are in the RBM at the CTD of the S1 domain (16). |
T109 |
1634-1781 |
Sentence |
denotes |
Of note, no amino acid change is seen in the RBM, which binds directly to the angiotensin-converting enzyme-2 (ACE2) receptor in SARS-CoV (16, 46). |
T110 |
1782-1889 |
Sentence |
denotes |
At present, the main emphasis is knowing how many differences would be required to change the host tropism. |
T111 |
1890-2020 |
Sentence |
denotes |
Sequence comparison revealed 17 nonsynonymous changes between the early sequence of SARS-CoV-2 and the later isolates of SARS-CoV. |
T112 |
2021-2213 |
Sentence |
denotes |
The changes were found scattered over the genome of the virus, with nine substitutions in ORF1ab, ORF8 (4 substitutions), the spike gene (3 substitutions), and ORF7a (single substitution) (4). |
T113 |
2214-2378 |
Sentence |
denotes |
Notably, the same nonsynonymous changes were found in a familial cluster, indicating that the viral evolution happened during person-to-person transmission (4, 47). |
T114 |
2379-2511 |
Sentence |
denotes |
Such adaptive evolution events are frequent and constitute a constantly ongoing process once the virus spreads among new hosts (47). |
T115 |
2512-2716 |
Sentence |
denotes |
Even though no functional changes occur in the virus associated with this adaptive evolution, close monitoring of the viral mutations that occur during subsequent human-to-human transmission is warranted. |