The predicted structures of SiCYS-N and SiCYS-C, and their sequence alignment with other phytocystatins. (A) The main three dimensional structure of SiCYS-N (2–88 a.a of SiCYS) and SiCYS-C (116–191 a.a. of SiCYS) shown in cartoon diagram was predicted by homology modeling using Orzyacystatin I (PDB: 1EQK) as template. The secondary structure elements corresponding to α-helices and β-sheets were shown in red and yellow. Three conserved motifs (G5, Q46XV48XG50, W77) were labeled. (B) SiCYS-N (1–88 a.a. of SiCYS) and SiCYS-C (89–199 a.a. of SiCYS) was aligned with Orzyacystatin I (term OC-I), AcCYS and CeCPI. The structures of Orzyacystatin I, AcCYS and CeCPI (2–92 a.a.) but not CeCPI (93–205 a.a.) were currently available in PDB. Amino acid residues identical at least five out of six aligned sequences were boxed in grey. Three conserved motifs were signed in red dot. A specific consensus sequence of phytocystatins, LARFAVXQHN, was marked in green upper line; while SN(S/T)L motif found in Ct extension marked in under line. The sequence corresponding to α-helice and β-sheets were signed in red and blue.