In celiac disease, the protein transglutaminase modifies gluten peptides by removing an amino group, which increases the likelihood of an immune response. These deaminated gluten peptides are then presented by MHC proteins, specifically HLA-DQ2 and HLA-DQ8, on the surface of antigen-presenting cells. This presentation is recognized by T-cell receptors, leading to an immune response that damages the intestinal lining. The interaction between these components triggers the autoimmune reaction of celiac disease.

Molecule Name(s): Transglutaminase, HLA-DQ2, HLA-DQ8, TRAV20

Source: Homo sapiens

Biological Role: Transglutaminase typically links two proteins together or, on single proteins, it removes an amino group from glutamine. HLA-DQ2 and HLA-DQ8 are major histocompatibility complex proteins that present peptide fragments to T-cells. TRAV20 is a T-cell receptor protein.

Associated Allergies: Celiac disease

References: PDB entries 2Q3Z, 1S9V, and 5KS9

Model 1: HLA-DQ2 MHC protein bound to deaminated gluten peptide (PDB entry 1S9V)

Model 2: HLA-DQ8 MHC protein presenting deaminated gluten peptide to T-cell receptor protein TRAV20 (PDB 5KS9)

Model 3: Transglutaminase bound to gluten peptide (PDB 2Q3Z)

Yellow: Gluten peptide (Chain B PDB 2Q3Z, Chain C PDB 1S9V, Chain J PDB 5KS9)

Blue: Transglutaminase (Chain A PDB 2Q3Z)

Greens: HLA-DQ2 (Chains A & B PDB 1S9V) and HLA-DQ8 (Chains A & B PDB 5KS9)

Purples: T-cell receptor TRAV20 (Chains G & H PDB 5KS9)