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-translational modification. Citrullination is distinct from the formation of the free amino acid citrulline as part of the urea cycle or as a byproduct of enzymes of the nitric oxide synthase family.
Uncombable hair syndrome (UHS) is a rare structural anomaly of the hair with a variable degree of effect. It is characterized by hair that is silvery, dry, frizzy, wiry, and impossible to comb. It was first reported in the early 20th century. It typically becomes apparent between the ages of 3 months and 12 years. UHS has several names, including “pili trianguli et canaliculi,” “cheveux incoiffables,” and “spun-glass hair.” This disorder is believed to be autosomal recessive in most instances, but there are a few documented cases where multiple family members display the trait in an autosomal dominant fashion. Based on the current scientific studies related to the disorder, the three genes that have been causally linked to UHS are PADI3, TGM3, and TCHH. These genes encode proteins important for hair shaft formation. Clinical symptoms of the disorder arise between 3 months and 12 years of age. The quantity of hair on the head does not change, but hair starts to grow more slowly and becomes increasingly “uncombable.” To be clinically apparent, 50% of all scalp hair shafts must be affected by UHS. This syndrome only affects the hair shaft of the scalp and does not influence hair growth in terms of quantity, textural feel, or appearance on the rest of the body.
In enzymology, a protein-arginine deiminase (EC 3.5.3.15) is an enzyme that catalyzes a form of post translational modification called arginine de-imination or citrullination:
Liver carboxylesterase 1 also known as carboxylesterase 1 is an enzyme that in humans is encoded by the CES1 gene. The protein is also historically known as serine esterase 1 (SES1), monocyte esterase and cholesterol ester hydrolase (CEH). Three transcript variants encoding three different isoforms have been found for this gene. The various protein products from isoform a, b and c range in size from 568, 567 and 566 amino acids long, respectively.
Beta-1,4-galactosyltransferase 1 is an enzyme that in humans is encoded by the B4GALT1 gene.
Protein-arginine deiminase type-4, is a human protein which in humans is encoded by the PADI4 gene. The protein as an enzyme, specifically protein-arginine deiminase, a type of hydrolase.
Glycine amidinotransferase, mitochondrial is an enzyme that in humans is encoded by the GATM gene.
Alpha-N-acetylgalactosaminidase is an enzyme that in humans is encoded by the NAGA gene.
Ornithine decarboxylase antizyme is an enzyme that in humans is encoded by the OAZ1 gene.
The RPS2 gene is the gene which, in humans, encodes the 40S ribosomal protein S2.
Ubiquitin conjugation factor E4 B is a protein that in humans is encoded by the UBE4B gene.
Peptidyl arginine deiminase, type III, also known as PADI3, is a protein which in humans is encoded by the PADI3 gene.
Peptidyl arginine deiminase, type I, also known as PADI1, is a protein which in humans is encoded by the PADI1 gene.
Peptidyl-prolyl cis-trans isomerase NIMA-interacting 4 is an enzyme that in humans is encoded by the PIN4 gene.
AMSH-like protease is an enzyme that in humans is encoded by the STAMBPL1 gene.
Acyl-CoA Synthetase, Bubblegum Family, member 1 (ACSBG1) is an enzyme that in humans is encoded by the ACSBG1 gene.
Mitochondrial tRNA-specific 2-thiouridylase 1 is an enzyme that in humans is encoded by the TRMU gene.
Peptidyl-prolyl cis-trans isomerase G is an enzyme that in humans is encoded by the PPIG gene.
Dehydrodolichyl diphosphate synthase is an enzyme that in humans is encoded by the DHDDS gene.
Aldehyde oxidase 1 is an enzyme that in humans is encoded by the AOX1 gene.
