Sequence alignments were generated and highlighted to show not just conserved residues but also peptidase preference. For each cleavage the residues P4-P4 0 were highlighted to indicate whether the residue in each sequence had been observed in any substrate at that position for the peptidase in question. Residues identical to the sequence where the cleavage is known are shown with a pink background. Replacements observed in other substrates are shown with an orange background. Where no substrate for this peptidase is known with this amino acid in this position the residue is shown with a black background. The term 'atypical' is used for an amino acid that has not been observed in a particular binding pocket in any known substrate for a peptidase.