Gliadin is a glycoprotein that, along with glutenin, plays a role in the formation of gluten, an ergastic amorphous mixture of proteins found in wheat, rye, and barley. Gluten is responsible for the elasticity of kneaded dough, which allows it to be leavened. Gliadin is approximately 60% soluble in ethanol and contains only intramolecule disulfide links. Gliadin is also found in a variety of foods as well as in beer, along with the glycoprotein Hordein. Induction of zonulin release in intestinal epithelial cells is triggered by Gliadin. This causes an activation of the zonulin pathway by PKC mediated cytoskeleton reorganization and tight junction opening leads to a rapid increase in intestinal permeability to macromolecules. Individuals with disorders such as celiac disease or Crohn's disease are sensitive to Gliadin since they lack the enzyme necessary for its digestion and can not tolerate it in their diet.
Function:
Celiac disease is associated with a CD4+ T-cell response to epitopes of gliadin presented by HLA-DQ2 or -DQ8 class II MHC molecules. These epitopes are present in a 33-mer peptide of wheat alpha-gliadin, residues 56-88, which is resistant to digestion and forms a substrate for tissue transglutaminase (TG2), generating the glutamic acid residues essential for binding to HLA-DQ2. The alcohol soluble proteins (prolamins) from wheat, rye, barley and oats produce the harmful effect of coeliac disease or gluten sensitive enteropathy in humans by causing characteristic changes in the intestinal mucosa. Patients so affected must avoid eating these grains and replace them with rice, corn, potatoes, etc. Many gluten-free foods are produced industrially, thus several immunoassays have been developed for determination of gliadin in supposedly gluten-free foods.
Subcellular Location:
Cytoplasmic; major seed storage protein in wheat.
SWISS:
N/A
Gene ID:
N/A
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