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. 2021 Jan 20;13(2):146. doi: 10.3390/v13020146

Figure 9.

Figure 9

Spike protein receptor binding domain showing the location of residues N439, Y453 and N501 (orange) surrounding the RGD motif (blue, space-fill). The double mutant Δ69/Δ70 often co-occurs with single-amino-acid replacements at these locations (N501Y, N439K and Y453F). Although residues 439 and 501 participate in ACE2-binding, Y453 does not [71]. This model is from pdb file 6M0J, in which the receptor-binding domain is bound to the ACE2 receptor (receptor not shown). Structural models in which the receptor-binding domain is unbound generally do not contain coordinates for residue 501 due to flexibility of the peptide chain between residues 499 and 504. The strategic location of this residue suggests that substitutions at this site could impact the availability of the RGD motif for binding to integrins.