NOTE.—For each protease, key residues for substrate specificity 189, 216, and 226 as well as predicted specificity as in Perona and Craik (1995). Secondary protein–protein interaction domains were identified by eye (CLIP domains) or from previous reports (Ross et al. 2003; Kelleher et al. 2007). More details on protein domains can be found at (http://pfam.sanger.ac.uk/). The symbol “?” indicates that the relevant site was not included in the EST sequence.