Figure 3.

Light-chain CDR3 tyrosine is required for insulin binding by VH125 family antibodies. (A) Alignment of CDR3 regions of VL genes from framework region cysteine at position 0, highlighting positive-charged residues (red), conserved residues among these CDR3s (bold-italics), and the QYxxxPP motif (blue); (B) retroviral light-chain expression on VH125, GFP+, IgM+ cells transduced with A12 (red), YF (purple dashed), or non-transduced GFP- (gray-filled) (left). Binding to labeled insulin by A12 compared to YF mutant and non-transduced GFP- (right). (C) Detection of receptor occupancy at multiple concentrations of unlabeled insulin using mAb123 normalized to IgM level. Shown are data representative of at least three experiments.