Prolamins are a group of plant

storage protein Storage proteins serve as biological reserves of metal ions and amino acids, used by organisms. They are found in plant seeds, egg whites, and milk. Ferritin is an example of a storage protein that stores iron. Iron is a component of heme, whic ...

s having a high

proline Proline (symbol Pro or P) is an organic acid classed as a proteinogenic amino acid (used in the biosynthesis of proteins), although it does not contain the amino group but is rather a secondary amine. The secondary amine nitrogen is in the prot ...

amino acid content. They are found in plants, mainly in the seeds of cereal grains such as

wheat Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...

(

gliadin Gliadin (a type of prolamin) is a class of proteins present in wheat and several other cereals within the grass genus ''Triticum''. Gliadins, which are a component of gluten, are essential for giving bread the ability to rise properly during baki ...

barley Barley (''Hordeum vulgare''), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains, particularly in Eurasia as early as 10,000 years ago. Globally 70% of barley pr ...

(

hordein 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. Horedeins are found in the endosperm where one of their functi ...

), rye (

secalin Secalin is a prolamin glycoprotein found in the grain rye, ''Secale cereale''. Secalin is one of the forms of gluten proteins that people with coeliac disease cannot tolerate, and thus rye should be avoided by people with this disease. It is gene ...

corn Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...

(

zein Zein is a class of prolamine protein found in maize (corn). It is usually manufactured as a powder from corn gluten meal. Zein is one of the best understood plant proteins.Momany, Frank A.; Sessa, David J.; Lawton, John C.; Selling, Gordon W.; H ...

sorghum ''Sorghum'' () is a genus of about 25 species of flowering plants in the grass family (Poaceae). Some of these species are grown as cereals for human consumption and some in pastures for animals. One species is grown for grain, while many othe ...

(

kafirin Kafirin is a class of prolamine storage protein found in grain sorghum ''Sorghum'' () is a genus of about 25 species of flowering plants in the grass family (Poaceae). Some of these species are grown as cereals for human consumption and some in ...

), and

oats The oat (''Avena sativa''), sometimes called the common oat, is a species of cereal grain grown for its seed, which is known by the same name (usually in the plural, unlike other cereals and pseudocereals). While oats are suitable for human con ...

(

avenin The oat (''Avena sativa''), sometimes called the common oat, is a species of cereal grain grown for its seed, which is known by the same name (usually in the plural, unlike other cereals and pseudocereals). While oats are suitable for human con ...

). They are characterised by a high

glutamine Glutamine (symbol Gln or Q) is an α-amino acid that is used in the biosynthesis of proteins. Its side chain is similar to that of glutamic acid, except the carboxylic acid group is replaced by an amide. It is classified as a charge-neutral, ...

and

content, and have poor solubility in water. They solubilise best in strong alcohol 0-80% light acid, and alkaline solutions. The prolamins of the tribe Triticeae, such as wheat

, and related proteins (see

Triticeae glutens Gluten is the seed storage protein in mature wheat seeds (and in the seeds of closely related species). It is the sticky substance in bread wheat which allows dough to rise and retain its shape during baking. The same, or very similar, proteins ...

) are known to trigger

coeliac disease Coeliac disease (British English) or celiac disease (American English) is a long-term autoimmune disorder, primarily affecting the small intestine, where individuals develop intolerance to gluten, present in foods such as wheat, rye and barle ...

, an autoimmune condition, in genetically predisposed individuals. Maize and sorghum prolamins are sorted by molecular weight into four classes, α, β, γ and δ. Alpha- and delta- prolamins cluster in a broad phylogenetic group (Group 1). The rest cluster into Group 2. Group 1 is widely duplicated in the two plants. A database of Triticeae prolamins (glutens) is available. There does not seem to be an analysis that tries to cluster both sources of prolamins into a grand classification.

References

External links

Pfam clan Prolamin
- a group of prolamin N-terminal domains with similar disulfide-bonding patterns Glycoproteins P {{protein-stub