MTARC2 (mitochondrial amidoxime reducing component 2) is a molybdenum-containing enzyme located on the outer mitochondrial membrane that catalyzes the reduction of N-hydroxylated compounds 1. As part of a three-component enzyme system with cytochrome b5 type B and NADH cytochrome b5 reductase, MTARC2 reduces various N-oxygenated substrates including amidoximes, acting as a metabolic counterpart to cytochrome P450 enzymes 1. The enzyme functions by cleaving N-OH bonds through electron transfer from NADH via the cytochrome b5 system 2. MTARC2 plays important roles in prodrug activation, particularly amidoxime-containing compounds that increase drug bioavailability, and detoxification pathways involving N-hydroxylated purines and pyrimidines 1. Recent studies suggest MTARC2 may regulate energy metabolism, as knockout mice show altered responses to Western diet feeding and different gut microbiota profiles compared to wild-type controls 3. Additionally, MTARC2 appears to function as a host restriction factor, with viral proteins like SARS-CoV-2 Orf9b showing differential interactions with MTARC2 in different species, potentially contributing to immune evasion mechanisms 4. The enzyme's physiological functions beyond xenobiotic metabolism remain largely unknown and warrant further investigation 1.