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In enzymology, a di-trans,poly-cis-decaprenylcistransferase (EC 2.5.1.31) is an enzyme that catalyzes the chemical reaction

di-trans,poly-cis-decaprenyl diphosphate + isopentenyl diphosphate ${\displaystyle \rightleftharpoons }$ diphosphate + di-trans,poly-cis-undecaprenyl diphosphate

Thus, the two substrates of this enzyme are di-trans,poly-cis-decaprenyl diphosphate and isopentenyl diphosphate, whereas its two products are diphosphate and di-trans,poly-cis-undecaprenyl diphosphate.

This enzyme belongs to the family of transferases, specifically those transferring aryl or alkyl groups other than methyl groups. The systematic name of this enzyme class is di-trans,poly-cis-decaprenyl-diphosphate:isopentenyl-diphosphate undecaprenylcistransferase. Other names in common use include di-trans,poly-cis-undecaprenyl-diphosphate synthase, undecaprenyl-diphosphate synthase, bactoprenyl-diphosphate synthase, UPP synthetase, undecaprenyl diphosphate synthetase, and undecaprenyl pyrophosphate synthetase. This enzyme participates in terpenoid biosynthesis.

As of late 2007, 15 structures have been solved for this class of enzymes, with PDB accession codes 1F75, 1JP3, 1UEH, 1V7U, 1X06, 1X07, 1X08, 1X09, 2D2R, 2DTN, 2E98, 2E99, 2E9A, 2E9C, and 2E9D.

• Muth JD, Allen CM (1984). "Undecaprenyl pyrophosphate synthetase from Lactobacillus plantarum: a dimeric protein". Arch. Biochem. Biophys. 230 (1): 49–60. doi:10.1016/0003-9861(84)90085-7. PMID 6712246.
• Takahashi I, Ogura K (November 1982). "Prenyltransferases of Bacillus subtilis: undecaprenyl pyrophosphate synthetase and geranylgeranyl pyrophosphate synthetase". J. Biochem. 92 (5). Tokyo: 1527–37. doi:10.1093/oxfordjournals.jbchem.a134077. PMID 6818223.