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. 2020 Nov 6;890:173720. doi: 10.1016/j.ejphar.2020.173720

Fig. 2.

Fig. 2

Spike glycoprotein gene schematics. The spike glycoprotein gene comprises of eight distinct segments. Residues 1–12 act as the Signal peptide (SP, Red). Residues 13–685 and 686–1273 indicate the S1 and S2 subunits of the spike glycoprotein respectively. The S1 subunit comprises of the N-Terminal Domain (NTD, residues 13–303, Olive green) and the Receptor-Binding Domain (RBD, residues 319–541, yellow). The RBD domain is further sub-divided into the C-Terminal Domain (CTD, residues 334–427, Pink) and the Receptor-Binding Motif (RBM, 437–508, Light blue). The cleavage site 1 (685–686) releases the S2 subunit which comprises of the Fusion Peptide region (FP: 788–806, Brown) followed by a second cleavage site (815–816) which generates the S2′ Domain (816–1273). The S2 subunit comprises of two heptad repeats HR1 (920–927) and HR2 (1163–1202) (Green) and two Coiled-Coil Regions CCR1 (949–993) and CCR2 (1176–1203) (Cyan) respectively. A transmembrane Helical Domain exists (1214–1234, Bright yellow) followed by a Topological Cytoplasmic Domain (TPC, 1235–1273, Magenta) which encompasses a Short Sequence Motif (SSF, 1269–1273, light red). The Extracellular Topological domain spans from residues 13–1213. (Colour, Double-column fitting image).