Fig. 2: Composition of SARS-CoV-2 S and alignment of S mutation points of SARS-CoV-2 variants.

a S can be proteolytically cleaved into S1 and S2 subunit. The S1 subunit contains the immunodominant N-terminal domain (NTD) and receptor-binding domain (RBD) as well as other subdomains. Fusion peptide (FP), heptad repeat 1 (HR1), heptad repeat 2 (HR2), transmembrane domain (TM), C-terminal peptide (CP) together with other unnamed parts comprise the S2 subunit. Names of the variants are labeled on both sides of the table. Mutation points are distinguished by different colors. Changes in Omicron-related strains are labeled with darker colors. Amino acid sequence of the index virus is included as a reference. At each given point, a hyphen means the amino acid is identical to that of the reference, Δ stands for deletion, ins stands for insertion, and various capital letters indicate substitutions. b Spatial positions of mutations in Alpha, Beta, Gamma, Delta, and Omicron variants are highlighted in structure models (PDB 6XR8).