ZPI contact residues in the ZPI-PZ complex interface. ZPI-PZ complex structure (pdb 3F1S) with ZPI in green and PZ pseudocatalytic and EGF2 domains in cyan. The reactive loop (RCL, red), sheet A (blue), helix A (orange), and helix G (purple) of ZPI are highlighted. The 6 ZPI residues of the contact interface in helix A, helix G, and sheet C are represented in stick.