Storage proteins serve as biological reserves of metal
ions and
amino acids
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...
, used by organisms. They are found in plant
seeds,
egg white
Egg white is the clear liquid (also called the albumen or the glair/glaire) contained within an egg. In chickens it is formed from the layers of secretions of the anterior section of the hen's oviduct during the passage of the egg. It forms arou ...
s, and
milk.
Ferritin is an example of a storage protein that stores
iron. Iron is a component of
heme, which is contained in the
transport protein,
hemoglobin and in
cytochromes.
Some storage proteins store amino acids. Storage proteins' amino acids are used in embryonic development of animals or plants. Two amino acid storage proteins in animals are
casein and
ovalbumin
Ovalbumin (abbreviated OVA) is the main protein found in egg white, making up approximately 55% of the total protein. Ovalbumin displays sequence and three-dimensional homology to the serpin superfamily, but unlike most serpins it is not a serine ...
.
Seeds, particularly of
leguminous plants, contain
high concentrations of storage proteins. Up to 25 percent of the dry weight of the seed can be composed of storage proteins. The best known storage protein in
wheat is the
prolamin
Prolamins are a group of plant storage proteins having a high proline amino acid content. They are found in plants, mainly in the seeds of cereal grains such as wheat (gliadin), barley (hordein), rye (secalin), corn (zein), sorghum (kafirin), and ...
gliadin, a component of
gluten.
References
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Storage proteins
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