Hordein is a prolamin glycoprotein, present in barley and some other cereals, together with gliadin and other glycoproteins (such as glutelins) coming under the general name of gluten. Hordein is a prolamin glycoprotein, present in barley and some other cereals, together with gliadin and other glycoproteins (such as glutelins) coming under the general name of gluten. Some people are sensitive to hordein due to disorders such as celiac disease or gluten intolerance.