Figure 4. Important virus-receptor binding motifs.

A. Binding of TGEV RBD mutants to cell surface pAPN. Relative binding (%) was determined for mutant to wild type SA proteins (see Materials and Methods). Substituted residues at the RBD tip that contact pAPN in the PRCV RBD-pAPN structure are shown in Figure 3, except for the V617Ngly mutant, with a glycan at RBD position 617 in the β5-β5b loop, outside the RBD tip (see Figure 3D). B. TGEV RBD binding to cell surface pAPN glycosylation mutants. Relative binding of the SA protein and the anti-HA mAb to HA-tagged pAPN proteins with (pAPN) or without the glycan linked to Asn736 (N736A and T738V). Mean and standard deviation for three experiments.