Fig. 5
From: Molecular basis of human CD22 function and therapeutic targeting
Antigenic surface of CD22 recognized by therapeutic antibody epratuzumab. a Epratuzumab heavy chain (dark teal) and light chain (light cyan) bind the CD22 d2 (wheat)/d3 (light green) interface as revealed by X-ray crystallography (bottom) and negative-stain EM (top). b Epratuzumab interactions with CD22 d2 are mediated by HCDRs, LCDR1, and LCDR3. c Epratuzumab interactions with CD22 d3. d The N231 glycan is part of the epratuzumab epitope. Composite omit electron density map for the N231 glycan GlcNAc2 residues (sticks) is shown as a blue mesh (1.0 σ contour level). Epratuzumab residues shown as sticks are buried by the N231 glycan. e Kinetics of epratuzumab binding to CD2220–687F, CD2220–687S, dCD2220–687, and CD2220–687F N231Q. Epratuzumab binds with higher affinity to CD22 with smaller N-linked glycans. The inset depicts examples of glycoforms likely to be present on CD22 from recombinant expression in HEK293F and HEK293S cells, and treated by EndoH. Error bars represent the standard error of the mean (SEM) derived from three independent BLI measurements
