(2E,6E)-farnesyl-diphosphate:isopentenyl-diphosphate farnesyltranstransferase may refer to: Hexaprenyl-diphosphate synthase ((2E,6E)-farnesyl-diphosphate specific), an enzyme All-trans-octaprenyl-diphosphate synthase, an enzyme All-trans-decaprenyl-diphosphate synthase, an enzyme