Features of I6 Cereal peptidase inhibitors. (A) Three-dimensional structure of a typical I1 inhibitor (1B1U). Cysteines are highlighted as balls and sticks and coloured in CPK. Red, α-helices; yellow, β-sheets. (B) Schematic PhyML phylogenetic tree using the selected Cereal sequences from the different plant species. Coloured triangles show clade-specific gene proliferations.