Wheat gluten peptides that the enzyme TG2 prefers
What it found
In lab tests, the enzyme TG2 in a wheat gluten digest preferred to modify 31 peptides, and most of these carried known celiac disease T-cell epitopes.
Two of the modified peptides were new candidates for T-cell epitopes.
What they found
Animal and lab studies
TG2 preferred substrates
Out of the complex gluten digest, 31 different peptides were tagged and identified as preferred substrates of TG2. The targeted glutamine residues were usually in a QXP motif, matching earlier findings on TG2 specificity.
Known T-cell epitopes
Most of the 31 peptides contained complete or partial versions of known gluten T-cell epitopes. For example, five of the nine alpha-gliadin peptides carried at least two of the DQ2-alpha-I, DQ2-alpha-II or DQ2-alpha-III epitopes.
Intact vs truncated epitopes
Epitopes that appeared as intact 9mer cores were frequently recognized by T cells from celiac patients, while those that appeared only as truncated versions were rarely recognized. The DQ2-gamma-II epitope was never seen as a complete 9mer but showed up in eight different truncated peptides.
New candidate epitopes
Two peptides that did not match any known T-cell epitope, peptide #19 and peptide #25, triggered responses in T-cell lines from celiac disease patients. These are new candidate T-cell epitopes.
Same peptide, two modifications
A few peptides were found with one glutamine transamidated and another deamidated at the same time. This could matter for how TG2-specific autoantibodies are made in celiac disease.
What the authors conclude
“TG2 as well as gastrointestinal proteolysis play important roles in the selection of gluten T-cell epitopes in celiac disease.”
Also in their conclusions
- They conclude that TG2 and gastrointestinal proteolysis both play important roles in selecting which gluten T-cell epitopes matter in celiac disease.
- They say that TG2 shows a clear preference for gluten peptides that are found as T-cell epitopes in celiac disease patients.
- They note that the T-cell epitopes frequently recognized by patient T cells more often remain intact than those that are infrequently recognized.
How it was done
The authors wanted to find out which peptides from a complex wheat gluten digest are the preferred targets of the enzyme TG2, because TG2 is thought to help select the gluten peptides that trigger celiac disease.
They digested whole wheat gluten with five digestive enzymes, then mixed the resulting peptides with TG2 and a tagging molecule. They used magnetic beads to pull out the tagged peptides and identified them by mass spectrometry. They also tested some of the identified peptides with T-cell lines from celiac disease patients.
What it can’t tell you
- This was a lab study using digested gluten and T-cell lines, not a study in people eating wheat.
- It cannot show whether these specific peptides cause symptoms or damage in a person with celiac disease.
- The T-cell tests used cells from a small number of patients, so the findings may not apply to everyone.
Who paid
- Conflicts
- Competing Interests: The authors have declared that no competing interests exist.
- Authors work at
- University of Oslo, Norway
The paper
- Title
- The preferred substrates for transglutaminase 2 in a complex wheat gluten digest are Peptide fragments harboring celiac disease T-cell epitopes
- Type
- Study
- Evidence
- Animals and lab studies
- Summarised from
- Full text
- Cite
- Dørum S, Arntzen MØ, Qiao SW, et al (2010). The preferred substrates for transglutaminase 2 in a complex wheat gluten digest are Peptide fragments harboring celiac disease T-cell epitopes. PloS one. doi:10.1371/journal.pone.0014056Free full textPubMed 21124911DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error