Partial MUSCLE alignment of putative platypus venom kallikrein serine protease sequences, showing the most conserved regions. The full alignment can be seen in Figure S5 in Additional file 1. Gilatoxin (P43685), blarina toxin (BAD18893), blarinasin (Q5FBW2), two snake sequences and two human tissue kallikreins are also shown (SWISS-PROT accession numbers are listed). The catalytic triad is highlighted in pink, and conserved cysteines highlighted in blue. Not all platypus venom peptides contain the triad and cysteines.