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. 2010 Nov 10;85(2):865–872. doi: 10.1128/JVI.01412-10

FIG. 5.

FIG. 5.

Analysis of the antigenic sites on HA63-286-RBD. (A) Conformational antigenic sites Sa, Sb, Ca, and Cb are mapped onto the HA63-286-RBD crystal structure (dark gray secondary structure elements within a semitransparent surface representation). The Ca site is formed from two subsites, Ca1 and Ca2, and they form a single contiguous antigenic site only when two protomers are adjacent in the HA trimer. (B to F) Zoomed-in views show an overlay of HA63-286-RBD (green) and the A/H1N1/2009 HA ectodomain (blue) at each antigenic site. The Cb site adopts variable backbone conformations, as seen in the two molecules of HA63-286-RBD (green), and the six molecules of A/H1N1/2009 HA ectodomain (blue) in their respective crystal structures. Similarly, some surface-exposed hydrophilic amino acid side chains (e.g., Q192 in the Sb site and R208 in the Ca1 site) can adopt variable conformations. The coordinates for A/H1N1/2009 HA ectodomain are from PDB entry 3LZG. All residues are labeled using H3 numbering as done in reference 5.