What is "trans-pentaprenyltranstransferase"

In enzymology, a trans-pentaprenyltranstransferase is an enzyme that catalyzes the chemical reaction

all-trans-pentaprenyl diphosphate + isopentenyl diphosphate $\rightleftharpoons$ diphosphate + all-trans-hexaprenyl diphosphate

Thus, the two substrates of this enzyme are all-trans-pentaprenyl diphosphate and isopentenyl diphosphate, whereas its two products are diphosphate and all-trans-hexaprenyl 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 all-trans-pentaprenyl-diphosphate:isopentenyl-diphosphate pentaprenyltranstransferase. Other names in common use include all-trans-hexaprenyl-diphosphate synthase, hexaprenyl diphosphate synthase, and hexaprenyl pyrophosphate synthetase. This enzyme participates in biosynthesis of steroids.