Since scientists love to classify things, we like to group proteins together into "families." Gliadin is a kind of protein called a prolamine. A prolamine is a protein which plants use to store energy and which dissolves in alcohol. Each grain has a different type of prolamine. As we've mentioned, wheat's prolamine is gliadin. Barley uses a prolamine called hordein, and corn uses one called zein. - See more at: http://www.quickanddirtytips.com/education/science/what-gluten#sthash.5eaPGxCg.dpuf