Figure 4

Variation of functional amino acid residues between Symbiodinium types and APX isoforms. Shown is a sequential alignment of residues involved in binding of heme (red), ascorbate (blue), hydrogen peroxide (cyan), and cations (proximal [orange] and distal [ochre]), as well as residues involved in the formation of the catalytic site (green) (sensu Figure 3). Differences are highlighted in relation to reference sequences (yellow) for hybrid ascorbate-cytochrome c peroxidases (SymAPX1 + 2) and typical ascorbate peroxidases.