This enzyme, characterized from eukaryotic organisms, catalyses the reduction of either (2E,4E)-2,4-dienoyl-CoA or (2E,4Z)-2,4-dienoyl-CoA to (3E)-3-enoyl-CoA. The best substrates for the enzyme from bovine liver have a chain-length of 8 or 10 carbons. Mammals possess both mitochondrial and peroxisomal variants of this enzyme. cf. EC 22.214.171.124, 2,4-dienoyl-CoA reductase [(2E)-enoyl-CoA-producing].