Figure 4. S51 in CDR2α is often used in TCRs and often engages MHC at the same site.

a. The Figure lists the CDR2 sequences of the human (h) and mouse (m) Vα regions that contain an S at position 51 (highlighted). V regions were omitted and numbered as in Figure 3a. b–m. Shown are the arrangements of MHC amino acids around S51α (in blue with red hydroxyl) in 8 (b–i) of the solved structures of TCRs bound to MHCI with the α2 helix of MHCI in magenta. Also indicated are the Vα region, MHC allele and pdb number. The structures are arranged from left to right and top to bottom roughly according the predicted strength of the interaction or alignment between S51α and MHCI, with no predicted contact for S51α in 2AK4 and 1FO0. j–m. As in b–i, but for TCRs bound to MHCII and with the β helix of MHCII in magenta. Structures were selected from the references in Figure 2.