Gliadin is the major seed storage protein in wheat. Substrate of transglutaminase. Causes an allergic reaction in human. Is the cause of the celiac disease, also known as celiac sprue or gluten-sensitive enteropathy (By similarity). The alpha/beta-gliadins can be divided into 5 homology classes. Sequence divergence between the classes is due to single base substitutions and to duplications or deletions within or near direct repeats. There are more than a 100 copies of the gene for alpha/beta-gliadin per haploid genome. Belongs to the gliadin/glutenin family.