Cis (Z)-Isoprenyl Diphosphate Synthases (cis-IPPS) catalyze the successive 1'-4 condensation of the isopentenyl diphosphate (IPP) molecule to trans,trans-farnesyl diphosphate (FPP) or to cis,trans-FPP to form long-chain polyprenyl diphosphates. A few can also catalyze the condensation of IPP to trans-geranyl diphosphate to form the short-chain cis,trans- FPP. In prokaryotes, the cis-IPPS, undecaprenyl diphosphate synthase (UPP synthase), catalyzes the formation of the carrier lipid UPP in bacterial cell wall peptidoglycan biosynthesis. Similarly, in eukaryotes, the cis-IPPS, dehydrodolichyl diphosphate (dedol-PP) synthase catalyzes the formation of the polyisoprenoid glycosyl carrier lipid dolichyl monophosphate. cis-IPPS form homodimers and are mechanistically and structurally distinct from trans-IPPS, which lack the DDXXD motifs, yet require Mg2+ for activity.
Jiyao W et al.(2023). "The conserved domain database in 2023.",