Figure 8.

The structure of zymogen matriptase, zSPD-S805A. A, the solved structure of zSPD-S805A (wheat) with the 60 loop, the 70 loop, the 170 loop, and the activation loop specified together with the residues in the catalytic triad and the S1 pocket (PDB entry 5LYO). B, the intact activation loop for zSPD-S805A (wheat) and the cleaved activation loop for activated matriptase (red). C, the zymogen triad for zSPD-S805A and activated matriptase, showing rearrangement of Asp⁸⁰⁴ (Asp¹⁹⁴). D, alignment of zSPD-S805A (wheat) and activated matriptase (gray), where the loops undergoing conformational changes are marked in red for activated matriptase. The S1 pocket is not formed in the zymogen.