alphagliadin

Alphagliadin, commonly referred to as alpha-gliadin, is a family of prolamin storage proteins found in wheat gluten. It is one of several gliadin fractions, alongside beta-, gamma-, and omega-gliadins, and contributes to the viscoelastic properties of dough. Alpha-gliadins are rich in glutamine and proline, and they are encoded by multiple gene families on the wheat genome (for example, Glu-1 loci on the A, B, and D genomes).

In terms of structure and genetics, alpha-gliadins are produced in the wheat endosperm and exist as several closely related proteins. The genes encoding these proteins are highly polymorphic, and individual wheat varieties contain diverse alpha-gliadin sequences. This diversity underpins differences in their immunogenic potential among wheat cultivars.

Alpha-gliadin is immunologically significant because it contains multiple T cell epitopes that can trigger immune responses in susceptible individuals. A prominent immunodominant peptide is a 33-mer fragment derived from alpha-gliadin, which is resistant to digestion and becomes highly proinflammatory after deamidation by tissue transglutaminase. In people with celiac disease, presentation of such epitopes by HLA-DQ2 or HLA-DQ8 molecules drives intestinal inflammation and mucosal damage.

Clinically, avoidance of gluten-containing foods—which include alpha-gliadins—is essential for individuals with celiac disease and often recommended for those with non-celiac gluten sensitivity or wheat allergy, though the underlying mechanisms differ. Research continues into breeding wheat varieties with reduced alpha-gliadin content and into enzymatic methods to detoxify immunogenic gliadin peptides.