<p>Sequences and secondary structures of alpha and beta chains in a Unified Residue Numbering for DR and DQ structures.</p>

The residue position in alpha and beta chains numbering corresponds to their numbering in the prototype structures 3PDO and 5KSU. The residue sequences for prototype structures are shown in the top line for each chain. The first and last position numbers of each helix and strand are shown in regular font. The position numbers of prototype residues in contact with peptide residues 3–14 are enlarged and bolded. Variations of residue content at these contacts in a given position are shown. For example, a contact position 54 in loop h1-h2 of DR alpha chain is occupied by C in the structure 3QXD but by F in all other structures. The hydrophobic residues are shown in italics. For example, the prototype DR alpha chain residue F in position 54 is hydrophobic, and shown in italics, while the variant residue C at the same position is not, and is shown in plain font. The position numbers of hydrophobic residues in the prototype structures are underlined. For example, position number 54 of the DR alpha chain is underlined, while position number 72 of the DQ alpha chain is shown in plain font, even though a variant residue I in that position is hydrophobic. Abbreviations: s1, s2… correspond to strand 1, strand 2, and so on; h1, h2… correspond to helix 1, helix 2, and so on. “Loop s1-s2” is a loop between strand 1 and strand 2. “Loop h1-h2 is a loop between helix 1 and helix 2, and similarly for the other loops. (XLSX)