Fig. 2

Schematic representation of the SARS-CoV-2 structure, genome and functional domain of SARS-CoV-2 S protein. The viral surface proteins, envelope membrane and spike, are embedded in a lipid bilayer, while the single-stranded positive-sense viral RNA (SS-RNA) is associated with the nucleocapsid protein. The spike proteins contain S1 and S2 subunits and the cleavage sites for furin and TMPRSS2. The spike proteins mediate the viral attachment to the host cells after activation by the enzyme TMPRSS2. SP, signal peptide; NTD, N-terminal domain; RBD, receptor-binding domain, contains core binding motif in the external subdomain; FP, fusion peptide; HR, heptad repeat 1 and heptad repeat 2; TM, transmembrane domain; CP, cytoplasm domain