Fig. 1.

Phylogenetic tree for selected members of the calpain family. The tree generated by FastTree is shown. Coloured branches indicate significant bootstrap values where light green is 100 %, dark green is >90 %, brown is >85 % and red >80 %. Tips are labelled with UniProt identifiers (where possible). Coloured dots indicate classification, additional domains and non-peptidase homologues, where brown is Bacteria, green is a signal peptide, pink is a transmembrane region, red is a CIII domain, yellow is an EF-hand structure domain, blue is a zinc-finger domain, orange is a C2 domain, turquoise is another additional domain, and black is a non-peptidase homologue. For the key to sequences, see Additional file 4: Table S2