Figure 5. Peptides distantly related to MCC show highly similar mechanism of recognition and linkages to the cognate antigen.
Crystal structures of TCR-pMHC complexes for 2B4-2A-I-Ek and 2B4-MCC-I-Ek (PDB ID: 3QIB) (A) and 5cc7-5c1-I-Ek and 226-MCC-I-Ek (PDB ID: 3QIU) (B) compared. TCR contacts are shown in magenta (top, noted with triangles). There is very little change in overall binding geometry despite significant variation of peptide sequence. The TCRs accommodate differences in peptide sequence primarily through differences in CDR3β (bottom). (C) TCR CDR loop footprints for 2B4 recognizing MCC and 2A peptides, 226 recognizing MCC and MCC K99E peptides, and 5cc7 recognizing 5c1 and 5c2 peptides show very little deviation. (D) Relationship between MCC and 2A peptides revealed through intermediate selected peptide sequences. See also Table S1 and Figure S5.