ent-Kaurene is a tetracyclic diterpene hydrocarbon and a biosynthetic intermediate of the plant hormone gibberellins. In flowering plants, ent-kaurene is biosynthesized from geranylgeranyl diphosphate (GGDP) by two distinct cyclases,ent-copalyl diphosphate synthase (CPS) and ent-kaurene synthase (KS).