Figure 4. Binding of selected RD2 TCR clones.

(a) Residues of A6 TCR used in the design of the RD2 library. The structures of the aligned wild-type A6:Tax/HLA-A2 (PDB: 1AO7)⁸ and A6-c134:Tax/HLA-A2 (PDB: 4FTV)⁴⁷, that contained the CDR sequences used as templates for the RD2 library, are shown with degenerate positions at D26α, G28α, S100α, W101α, and L98β (green). The binary residues (Gln or Thr) at position Q30α is shown in red, and the backbone of the binary strings of wild-type “AGGR” or high-affinity “MSAQ” in positions 99-102β are shown in yellow. The Tax peptide is in black, the MART1 peptide from the aligned Mel5:MART1/HLA-A2 structure (PDB: 3HG1)⁷ is in green, and the WT1 peptide from the aligned WT1/HLA-A2 structure (PDB: 3HPJ)⁶⁸ is in cyan (b) A Tax-selected clone (RD2-Tax-S3-1) (left panels), a MART1-selected clone (RD2-MART1) (middle panels), and a WT1-selected clone (RD2-WT1-1) were each stained with various concentrations of the indicated peptide/HLA-A2-Ig dimers. Gray filled histograms were yeast cells stained with secondary antibody only. Data is representative of 3 experiments with similar results.