Investigation of multiple forms of Tri a Bd 27K, a major wheat allergen, by immunoblotting analysis. Tri a Bd 27K, a major wheat allergen, is a glycoprotein. Tri a Bd 27K was found to occur in multiple forms by two-dimensional polyacrylamide gel electrophoresis and immunoblotting with a monoclonal antibody against the allergen. Furthermore, it was found that only Tri a Bd 27K components, which have N-linked glycan moieties with fucose residues, bound to IgE antibodies in the sera of wheat-sensitive patients.