Fig. 1

Diagrammatically demonstrates the substrate binding pockets S4-S3’ of PR3 with substrate cleavage positions P4-P3’, according to the Schechter and Berger enzyme-ligand binding site numbering convention [19]. The arrows indicate the sites for Val/Ala-containing peptide cleavage and hydrophobic residue binding sites, whilst + indicates positive and – indicates negative residue binding site. Adapted from [13]