Crystal structure of the GA101-CD20 epitope peptide complex. (A) Overall structure of the complex as a ribbon model. The GA101 Fab is shown with the light chain in blue, the heavy chain in green, and the CD20 epitope peptide in orange. The superimposed GA101 Fab alone showed only minor structural changes and is colored in gray. (B) Stereo view of the final 2FO-FC electron density map for the bound CD20 epitope peptide countered at 1σ. The ordered part of the peptide comprising residues 163-187 is shown as color-coded stick model and the Fab fragment as surface representation. (C) Detailed view of the CDR of GA101 binding to the CD20 epitope peptide (sequence) showing the hydrogen bonds mediating the interaction. The left panel shows the interactions of residues ¹⁷⁰ANPS¹⁷³ and the right panel hydrogen network of residues ¹⁷⁴EKN¹⁷⁶. A bound chloride ion at the interface is depicted as a green sphere. Color coding of GA101 and CD20 is the same as in panel A.