数据之源，洞见之始

Metabolite Card

Note

all-trans-Hexaprenyl diphosphate is the final product of the hexaprenyl diphosphate biosynthesis pathway. In this pathway, multiple units of isopentenyl diphosphate (IPP) undergo a series of polymerizations to form various polyisoprenoids. There are two different pathways for the biosynthesis of IPP. Bacteria that possess ubiquinone generally use the methylerythritol phosphate pathway (MEP), while the eukaryotic microorganisms use the mevalonate pathway. However, exceptions exist. For example, some eukaryotic microbes, like the green algae and the malarial parasite Plasmodium falciparum, appear to utilize the MEP pathway, and some bacteria utilize the mevalonate pathway (Eisenreich01, Eisenreich04). In Saccharomyces cerevisiae S288C, the initial addition of two isoprenyl units to form (E, E)-farnesyl diphosphate is catalyzed by geranyltransferase / dimethylallyltransferase, encoded by FPP1. An additional unit is added by farnesyltranstransferase (encoded by BTS1), resulting in the formation of all-trans-geranyl-geranyl diphosphate. The last enzyme in this pathway is hexaprenyl diphosphate synthase (encoded by COQ1), which adds additional isoprenoid units to a maximal length unique to the organism. In the case of Saccharomyces cerevisiae S288C, it is 6 units. Polyprenyl diphosphate synthase enzymes, such as hexaprenyl diphosphate synthase, are responsible for determining the final length of the tail. When yeast COQ1 mutants are complemented with homologs from other organisms, ubiquinone biosynthesis is restored, but the tail length of the quinone depends on the source of the enzyme.