Fig. 2.

Schematic diagram of coronavirus particle and S protein gene partitioning. (a) Major structural proteins of the coronavirus particle include Spike glycoprotein (S protein); Membrane (M) protein; Nucleocapsid (N) protein; and Envelope (E) protein. (b) The S protein is mainly divided into S1 and S2 subunits and subdivided again into signal peptide (SP); N-terminal domain (NTD); receptor-binding domain (RBD), which contains receptor binding motif (RBM); fusion peptide (FP); heptad repeat region 1 (HR1); heptad repeat region 2 (HR2); transmembrane region (TM); and cytoplasmic tail (CP) according to different functions