Peptidyl arginine deiminase, type III, also known as PADI3, is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
which in humans is encoded by the ''PADI3''
gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
.
This gene encodes a member of the
peptidyl arginine deiminase family of enzymes, which catalyze the post-translational
deimination
Citrullination or deimination is the conversion of the amino acid arginine in a protein into the amino acid citrulline. Citrulline is not one of the 20 standard amino acids encoded by DNA in the genetic code. Instead, it is the result of a post-tr ...
of proteins by converting
arginine residues into
citrulline
The organic compound citrulline is an α-amino acid. Its name is derived from ''citrullus'', the Latin word for watermelon. Although named and described by gastroenterologists since the late 19th century, it was first isolated from watermelon in 1 ...
s in the presence of calcium ions. The family members have distinct substrate specificities and tissue-specific expression patterns. The type III enzyme modulates hair structural proteins, such as
filaggrin
Filaggrin (filament aggregating protein) is a filament-associated protein that binds to keratin fibers in epithelial cells. Ten to twelve filaggrin units are post-translationally hydrolyzed from a large profilaggrin precursor protein during termi ...
in the
hair follicle and
trichohyalin
Trichohyalin is a protein that in mammals is encoded by the ''TCHH'' gene.
Discovery
In 1903 the name ''trichohyalin'' was assigned to the granules of the inner root sheath (IRS) of hair follicles discovered by Hans Vörner. In 1986 the name was ...
in the inner root sheath, during hair follicle formation. Together with the type I enzyme, this enzyme may also play a role in terminal differentiation of the
epidermis
The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the amount of water rele ...
. This gene exists in a cluster with four other
paralogous
Sequence homology is the biological homology between DNA, RNA, or protein sequences, defined in terms of shared ancestry in the evolutionary history of life. Two segments of DNA can have shared ancestry because of three phenomena: either a sp ...
genes.
See also
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Protein-arginine deiminase
In enzymology, a protein-arginine deiminase () is an enzyme that catalyzes a form of post translational modification called arginine de-imination or citrullination:
:protein L-arginine + H2O \rightleftharpoons protein L-citrulline + NH3
Thus, ...
References
Further reading
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