From glycolysis and the mevalonate pathway, diphosphomevalonic acid can be reacted with ATP to produce isopentenyl diphosphate which can be used in many reactions due to it's phosphate groups. Isopentenyl can be converted into geranyl pyrophosphate through two different paths, with one having an intermediate of dimethylallylpyrophosphate. Geranyl pyrophosphate itself can be used in monoterpenoid biosynthesis but more importantly, it can converted into (E,E)- farnesyl diphosphate through farnesyl pyrophosphate synthase. With (E,E)-farnesyl diphosphate and isopentenyl diphosphate, many reactions can take place depending on the number of substrates are used and how many phosphate groups are to be transferred. The products from the reactions are usually substrates for other biosynthesis pathways like N-glycan biosynthesis, carotenoid biosynthesis, diterpenoid biosynthesis, steroid biosynthesis and ubiquinone and other terpenoid quinone biosynthesis pathways. (E,E) farnesyl diphosphate can also be combined with a cysteine protein to make S-farnesyl protein. S-Farnesyl protein can have the c-terminal removed and then can be trans methylated by S-adenosylmethionine to eventually make farnesylcysteine. Through unknown processes farnesylcysteine can be converted can converted back to (E,E) farnesyl diphosphate, but not all the enzymes are known yet.

Terpenoid Backbone Biosynthesis References