Acyl-coenzyme A synthetases catalyse the activation of fatty acids by thioesterification to CoA, the fundamental initial reaction in fatty acid oxidation. Members of the long chain acyl-coenzyme A synthetases (ACSVL) subfamily were originally thought to be fatty acid transport proteins (FATPs), hence their approved gene names and symbols are “solute carrier family 27 (fatty acid transporter) member x" (SLC27Ax) but their transport function has never been proven. Instead, their amino acid sequence contains two highly conserved motifs characteristic of acyl-CoA synthetases. Long-chain fatty acid transport protein 3 (Slc27a3, aka Acsvl3, Fatp3) preferentially ligates CoA-SH to very long-chain fatty acids (VLCFA) (Pei et al. 2004).