Conversely, under intracellular conditions, low calcium concentrations favour a compact “closed” conformation, allowing the GTP binding site to form and occluding the transamidase site.5–8 Dysregulation of either function has been linked to pathologies including celiac diseases,9 fibrosis,10 and cancer,11,12 making hTG2 an attractive therapeutic target. The gene discussed is TGM2; the disease is celiac disease.