Figure 4.

Binding of epitope peptides to the classic MHC I and MHC II molecules. The human MHC I class molecule (HLA-A∗0201, blue) and MHC II class molecule (HLR-DR1, purple) are bound to the peptide LLFGYPVYV (left, PDB ID:1HHK) and the peptide PKYVKQNTLKLAT (right, PDB ID:1FYT), respectively. Stick views of peptides are used to display their binding grooves with MHC I and MHC II molecules. The arrows indicate the critical positions for binding with MHC molecules (in pink) and binding to TCRs (in rose red), numbered P1–P9. The function of the unnumbered pockets depends on the specific MHC molecules. Figures were generated by PyMOL.