ACOX3 Background Information ACOX3 (acyl-Coenzyme A oxidase 3), also known as BRCOX or PRCOX, is a 700 amino acid protein that localizes to peroxisomes and belongs to the acyl-CoA oxidase family. Using FAD as a cofactor, ACOX3 catalyzes the desaturation of 2-methyl branched fatty acids in peroxisomes, thereby playing an important role in peroxisomal fatty acid beta-oxidation. Human ACOX3 shares 75% sequence identity with its rat counterpart, suggesting a conserved role between species. Multiple isoforms of ACOX3 exist due to alternative splicing events. The gene encoding ACOX3 maps to human chromosome 4, which encodes nearly 6% of the human genome and has the largest gene deserts (regions of the genome with no protein encoding genes) of all of the human chromosomes. Defects in some of the genes located on chromosome 4 are associated with Huntington's disease, Ellis-van Creveld syndrome, methylmalonic acidemia and polycystic kidney disease.