Figure 2.

Overview of the Taxol biosynthetic pathway. The boxed MEP Pathway is the plastidial route from pyruvate and glyceraldehyde 3-phosphate (via methylerythritol phosphate) for C₅ (IPP and DMAPP) precursor supply. The abbreviations are: IPP, isopentenyl diphosphate; DMAPP, dimethylallyl diphosphate; IPPI, isopentenyl diphosphate isomerase; GGPPS, geranylgeranyl diphosphate synthase; TS, taxadiene synthase; and PAM, phenylalanine aminomutase. OPP denotes the diphosphate moiety; Ac and Bz denote acetyl and benzoyl groups, respectively. Because the relative order of C1 hydroxylation and oxetane formation is uncertain, the hypothetical intermediate illustrated could be at the level of an acylated hexaol rather than a heptaol bearing the C1 hydroxyl.