Epitope

An epitope is the molecular feature recognized by an antibody. Protein denaturation can expose an epitope or destroy the spatial arrangement required for its recognition; an antibody that works on a folded protein need not work in SDS-PAGE-based Western blot antibody detection.

Epitope mapping investigates which target regions or residues contribute to recognition by an antibody. Loss of binding after a target mutation must be distinguished from target misfolding or loss of expression.