Figure 2.

The carotenoid biosynthetic pathway. The names of the major carotenoids present in C. reinhardtii are in bold. Pigments in brackets have not yet been observed in C. reinhardtii. Full enzyme names are as follows: DXS, 1-deoxy-d-xylulose-5-phosphate synthase; DXR, 1-deoxy-d-xylulose-5-phosphate reductoisomerase; CMS, 4-diphosphocytidyl-2-C-methyl-d-erythritol synthase; CMK, 4-diphosphocytidyl-2-C-methyl-d-erythritol kinase; MCS, 2-C-methyl-d-erythritol 2,4-cyclodiphosphate synthase; HMS, 1-hydroxy-2-methyl-2-(E)-butenyl-4-diphosphate synthase; IDS, isopentenyl diphosphate:dimethylallyl diphosphate synthase; IDI, isopentenyl diphosphate:dimethylallyl diphosphate isomerase; GGPS, geranylgeranyl pyrophosphate synthase; PSY, phytoene synthase; PDS, phytoene desaturase; ZDS, ζ-carotene desaturase; CRTISO, carotenoid isomerase; LCYB, lycopene β-cyclase; LCYE, lycopene ɛ-cyclase; CHYB, carotene β-hydroxylase; CHYE, carotene ɛ-hydroxylase; ZEP, zeaxanthin epoxidase; VDE, violaxanthin deepoxidase; NSY, neoxanthin synthase; LSY, loroxanthin synthase; BKT, carotene β-ketolase; and GGR, geranylgeranyl reductase. In the case of multiple commonly used synonyms, see Grossman et al. (2004); abbreviations indicative of enzymatic function were preferred. Throughout the text, the same abbreviations, in capital letters, are used for protein and gene designations, the latter being italicized. For chemical structures of intermediates in the MEP pathway, see Rodriguez-Concepcion and Boronat (2002), and for chemical structures of later intermediates, see Cunningham and Gantt (1998) or Hirschberg (2001).