Epitope Mapping: B-cell Epitopes

Immunoglobulin molecules are folded in a way that assembles sequences from the variable regions of both the heavy and light chains into a surface feature (comprised of up to six complementarity-determining regions (CDRs)) that is complementary in shape to a surface structure on the antigen. These two surface features, the ‘paratope’ on the antibody and the ‘epitope’ on the antigen, may have a certain amount of flexibility to allow an ‘induced fit’ between them. In the narrow sense, epitope mapping is the process of locating the antibody-binding site on the antigen. The term is also applied in a broader sense to T-cell epitopes (Stern and Wiley, 1994) and has even been applied to receptor–ligand interactions unrelated to the immune system. Only B-cell epitopes are relevant to the biochemical understanding of antibody–antigen interactions. See also: Antibodies; Immunoglobulin Fold: Structures of Proteins in the Immunoglobulin Superfamily