The function of ENSG00000104325 (DECR1, 2,4-dienoyl-CoA reductase 1) is as follows. Auxiliary enzyme in the beta-oxidation of mono- and polyunsaturated fatty acids (Probable) (PubMed:15531764, PubMed:26474213). Together with the Enoyl-CoA delta isomerase 1 (ECI1) and the Delta(3,5)-Delta(2,4)-dienoyl-CoA isomerase (ECH1) they allow reentrance of the enoyl-CoA into the beta-oxidation cycle (PubMed:26474213). It participates in the metabolism of unsaturated fatty enoyl-CoA esters having double bonds in both even- and odd- numbered positions in mitochondria (PubMed:15531764). Acts primarily on polyunsaturated fatty acids (Probable). Catalyzes the NADP-dependent reduction of 2,4-dienoyl-CoA to yield trans-3-enoyl-CoA (PubMed:15531764). Based on its established catalytic mechanism, it is predicted to act also on other fatty acids besides those tested experimentally (Probable). {ECO:0000269|PubMed:15531764, ECO:0000303|PubMed:26474213, ECO:0000305|PubMed:26474213, ECO:0000305|PubMed:32427840}.