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. a very-long-chain (3R)-3-hydroxyacyl-CoA = a very-long-chain (2E)-enoyl-CoA + H2O (3R)-hydroxyhexadecanoyl-CoA = (2E)-hexadecenoyl-CoA + H2O (3R)-hydroxyoctadecanoyl-CoA = (2E)-octadecenoyl-CoA + H2O (3R)-hydroxyeicosanoyl-CoA = (2E)-eicosenoyl-CoA + H2O (3R)-hydroxydocosanoyl-CoA = (2E)-docosenoyl-CoA + H2O (3R)-hydroxytetracosanoyl-CoA = (2E)-tetracosenoyl-CoA + H2O (3R)-hydroxyhexacosanoyl-CoA = (2E)-hexacosenoyl-CoA + H2O Lipid metabolism; fatty acid biosynthesis. May interact with enzymes of the ELO family (including ELOVL1); with those enzymes that mediate condensation, the first of the four steps of the reaction cycle responsible for fatty acids elongation, may be part of a larger fatty acids elongase complex. Interacts with BCAP31. Belongs to the very long-chain fatty acids dehydratase HACD family. Shares some similarity with tyrosine phosphatase proteins but it has probably no phosphatase activity.