Catalyzes the third of the very long-chain fatty acids (VLCFA) elongation four-step cycle (condensation, reduction, dehydration, and reduction). This endoplasmic reticulum-elongation process is characterized by the addition of two carbons to the lipid chain through each cycle. This enzyme catalyzes the dehydration of the 3-hydroxyacyl-CoA intermediate into trans-2,3-enoyl-CoA, within each cycle of elongation. Therefore, it participates in the production of various VLCFAs involved in multiple biological processes as precursors of membrane lipids and lipid mediators.
