Calcium-binding allergens: From plants to man

Calcium-binding proteins contain a variable number of motifs termed EF- han ds, which consist of two perpendicularly placed alpha-helices and an interh elical loon forming a single. calcium-binding Site. Due to their ability to bind and transport calcium as well as to interact with a variety of ligand s in a calcium-dependent manner, they fulfill important biological function s in eukaryotic cells. After parvalbumin, a three EF-hand fish allergen, ca lcium-binding allergens were discovered in pollens of trees, grasses and we eds and, recently, as autoallergens in man. Although only a small percentag e of atopic individuals displays IgE reactivity to calcium-binding allergen s, these allergens may be important because of their ability to cross-sensi tize allergic individuals. Conformation and stability as well as IgE recogn ition of calcium-binding allergens greatly depend on the presence of protei n-bound calcium ions. It is thus likely that hypoallergenic derivatives of calcium-binding allergens can be engineered by recombinant DNA technology f or immunotherapy of sensitized patients.