Acyl Coenzyme A Synthetase Medium Chain Family, Member 2B (ACSM2B)

The purification of xenobiotic/medium-chain fatty acid:CoA ligases (XM-ligases) from human liver mitochondria resulted in the isolation of two chromatographically separable forms (HXM-A and HXM-B). Identical sequences were obtained for HXM-A and HXM-B for the two peptides. These sequences were used to design probes for screening a human liver cDNA library. This resulted in the isolation of two overlapping cDNAs. This protein bears 56.2% amino acid homology to the MACS1 (medium-chain acyl-CoA synthetase) enzyme, 58.7% homology to the bovine XL-III XM-ligase, and 81.5% homology to the bovine XL-I XM-ligase. The cDNA could be expressed in COS cells, and the expressed enzyme had greater benzoate activity than phenylacetate activity, which is consistent with the known substrate specificity of HXM-A.