Farnesyl pyrophosphate synthase; part of the second module of ergosterol biosynthesis pathway that includes the middle steps of the pathway (By similarity). The second module involves the formation of farnesyl diphosphate, which is also an important intermediate in the biosynthesis of ubiquinone, dolichol, heme and prenylated proteins (By similarity). This module also plays a key role in the biosynthesis of triterpenes such as ganoderic acids (GA), a group of highly oxygenated lanostane-type triterpenoids which are well recognized as a main group of unique bioactive compounds in the medicinal mushroom Ganoderma lucidum (PubMed:22203490, PubMed:31253150). Activity by the mevalonate kinase first converts mevalonate into 5-phosphomevalonate (By similarity). 5-phosphomevalonate is then further converted to 5-diphosphomevalonate by the phosphomevalonate kinase (By similarity). The diphosphomevalonate decarboxylase MVD then produces isopentenyl diphosphate (PubMed:22203490). The isopentenyl-diphosphate delta-isomerase then catalyzes the 1,3-allylic rearrangement of the homoallylic substrate isopentenyl (IPP) to its highly electrophilic allylic isomer, dimethylallyl diphosphate (DMAPP) (By similarity). Finally the farnesyl diphosphate synthase FPS catalyzes the sequential condensation of isopentenyl pyrophosphate with dimethylallyl pyrophosphate, and then with the resultant geranylpyrophosphate to the ultimate product farnesyl pyrophosphate (PubMed:18540102, PubMed:31253150). dimethylallyl diphosphate + isopentenyl diphosphate = (2E)-geranyl diphosphate + diphosphate (2E)-geranyl diphosphate + isopentenyl diphosphate = (2E,6E)-farnesyl diphosphate + diphosphate Binds 2 Mg(2+) ions per subunit. Isoprenoid biosynthesis; farnesyl diphosphate biosynthesis; farnesyl diphosphate from geranyl diphosphate and isopentenyl diphosphate: step 1/1. Isoprenoid biosynthesis; geranyl diphosphate biosynthesis; geranyl diphosphate from dimethylallyl diphosphate and isopentenyl diphosphate: step 1/1. Expression is induced in ganoderic acid (GA) producing conditions. Belongs to the FPP/GGPP synthase family.