Figure 1.

Schematic representation of xanthophyll synthesis in red algae. DOXP-synthase (DXS), DOXP reductoisomerase (DXR), isopentenyl pyrophosphate (IPP), dimethylallyl pyrophosphate (DMAPP), geranylgeranyl pyrophosphate (GGPP), GGPP synthase (GGPPS), phytoene synthase (PSY), phytoene desaturase (PDS), z-carotene desaturase (z-CDS), lycopene β-cyclase (LCYB), lycopene ε-cyclase (LCYE), and zeaxanthin epoxidase (ZEP). The lightning symbol indicates that light has an effect over the carotenogenic gene expression of the enzyme. The upstream lycopene synthesis pathway is as described for plants and algae, modified from [20]. Downstream of lycopene corresponds to the synthesis pathways particularly of Pyropia yezoensis, although enzymes unique to Bangiales have not yet been described; modified from [21].