Fig. 1. Structural overview of peptide-MHC I complexes using the crystal structure of HLA-B*35:01 in complex with VY8(P5A), PDB ID: 1A1N: (a) the α₁- and α₂-domain (blue and cyan, respectively) form the binding groove, which hosts the antigenic peptide (yellow) and is supported by β₂-microglobulin (β₂m, gray). The α₃-domain (purple) attaches the MHC I to the cell surface via a membrane tether and a cytosolic loop, which were both not resolved in the crystal structure. (b) In the binding groove, the anchor residues P2 and Y8 (yellow licorice) of the antigenic peptide are in close contact with Y99 and S116 (cyan licorice) in the B- and F-pocket of the binding groove, respectively. The approximate positions of the pockets A–F are indicated in red; the backbones of both Y99 and S116 are located outside, but their side chains point into the B- and F-pocket, respectively. In the complex formed by HLA-B*44:02 and EF9, E2 and F9 are close to Y99 and D116, respectively (not shown). The α₃-domain and β₂m are omitted for clarity in panel b.