Figure 1. Amino acid alignment of cystatins. The numbering refers to the first residue of the mature protein. Dashes indicate gaps introduced to optimize alignments. Boxes indicate residues that are involved in inhibition of papain-like cysteine proteases. The dashed box indicates a domain involved in the inhibition of legumain. Shaded areas indicate residues in cystatins capable of inhibiting legumain. Solid brackets indicate disulfide bridges in members of family 2 and 3 cystatins, dashed bracket indicates a disulfide bridge unique to cystatin F, and the double bracket indicates a disulfide bridge present in kininogen domains D2 and D3. The N-glycosylation sites in cystatins E/M and F are indicated by bold, underlined N's (asparagine). The bold, underlined S's (serine) in cystatin S indicate phosphorylation sites and that in cystatin M indicate a potential phosphorylation site.