fig1

Figure 1. Structural characteristics of cathepsin C. (A) Schematic representation of the (pro)cathepsin C structure; (B) Schematic representation of the active site of papain-like peptidases adapted for cathepsin C. The substrate binding sites on the enzyme are labeled S3 through S2'. The substrate is presented with white circles corresponding to individual residues and residues P2 through P2' are labelled. The arrow denotes the scissile bond; (C) Three-dimensional structure of a cathepsin C subunit. The peptidase domain is shown in molecular surface representation and the exclusion domain in cartoon representation. Active site residues Cys234 and His381 are colored yellow and blue, respectively, Asp1 is shown as red sticks, and the chloride ion cofactor as a green sphere; (D) The cathepsin C tetramer shown in cartoon representation. Exclusion domains are colored blue and peptidase domains are colored tan, respectively. Coordinates were retrieved from the Protein Data Bank under accession code 1K3B.