Figure 2.

Humanizing H1 amino acid variants and IAV hemagglutinin and receptor-binding site structures.A, effects of individual receptor-binding variants on viral receptor specificity that contributed to H1N1 entry into humans. B, overall structure of the HA (H1) hemagglutinin trimer shown as a transparent surface. HA1 and HA2 subunits from one protomer of the trimer are highlighted in red and green, respectively. C, architecture and key structural features of avian (green) and human (pink) H1. The locations of key amino acid positions are highlighted through depiction of Cα positions as enlarged spheres and via labeling of key residues and secondary structural features. Assembled in Pymol (Schrodinger LLC) using PDB IDs: 1RV0 and 1RVZ.