FIG. 1.

Tocopherol and plastoquinone biosynthetic pathways in A. thaliana, Synechocystis sp. strain PCC 6803, and C. reinhardtii. Differences in the methylation step of MPBQ and MSBQ are shown. Question marks indicate unknown enzymes or that the function of a specific enzyme has not be proven, and the “and/or” indicates a possibility of functional redundancy or that another enzyme is responsible for the function. TMT, γ-tocopherol methyltransferase; HPP, p-hydroxyphenylpyruvate; HPPD, p-hydroxyphenylpyruvate dioxygenase; HPT, homogentisate phytyltransferase; HST, homogentisate solanesyltransferase; MPBQ/MSPQ MT, MPBQ/MSBQ methyltransferase; phytyl-DP, phytyldiphosphate; solanesyl-DP, solanesyldiphosphate; TC, tocopherol cyclase.