Gluten

right|thumb|upright=1.30|Examples of sources of gluten (clockwise from top): wheat as flour, spelt, barley, and rye as rolled flakes

thumb|Commercially packaged seitan

thumb|Gliadin Gliadin (a type of prolamin) is a class of proteins present in wheat and several other cereals within the grass genera Triticum and Hordeum. Gliadins, which are a component of gluten, are essential for giving bread the ability to rise properly during baking. Gliadins and glutenins are the two main components of the gluten fraction of the wheat seed. This gluten is found in products such as wheat flour. Gluten is split about evenly between the gliadins and glutenins, although there are variations found in different sources.

Glutenin (a type of glutelin) is a major protein within wheat flour, making up 47% of the total protein content. The glutenins are protein aggregates of high-molecular-mass (HMW) and low-molecular-mass (LMW) subunits with molar masses from about 200,000 to a few million, which are stabilized by intermolecular disulfide bonds, hydrophobic interactions and other forces. Glutenin is responsible for the strength and elasticity of dough.

Glutelins are a class of prolamin proteins found in the endosperm of certain seeds of the grass family. They constitute a major component of the protein composite collectively referred to as gluten. Glutenin is the most common glutelin, as it is found in wheat and is responsible for some of the refined baking properties in bread wheat. The glutelins of barley and rye have also been identified. Glutelins are the primary protein form of energy storage in the endosperm of rice grains.