Fig. 2.

Acidic residue D101 of AL-57 is critical for binding. (A) Primary sequence of variable regions of AL-57. The CDRs are shown in bold and are underlined. The beginning of a constant region is underlined with a dashed line. (B) Binding of parental and mutant AL-57 IgG (3 μg/ml) to the isolated, locked HA I domain expressed on K562 cells was examined by immunofluorescent flow cytometry in the presence of 1 mM Mg²⁺ (filled histograms) or 5 mM EDTA (open histograms). Binding of AL-57^D101A in Mg²⁺ and EDTA is hardly distinguishable from background binding of control IgG.