Cloning and functional expression of a novel long-chain acyl-CoA synthetase expressed in brain.

Complementary DNA clones encoding a protein highly homologous to the previously characterized long-chain acyl-CoA synthetase (LACS) in liver were isolated from rat brain cDNA libraries. This protein consists of 697 amino acids and has 64.7% identity with the rat liver LACS sequence. The brain protein and the liver LACS share essentially the same domain structure, having two regions similar to those of click beetle luciferase and a long discrete gap flanking the similar domains. A significant sequence similarity was found between the brain protein and malaria octapeptide-repeat antigen, suggesting a functional similarity. COS cells transfected with the cDNA for the brain protein expressed LACS activity with slightly different fatty acid specificity from that of the liver LACS. This new LACS is expressed predominantly in brain and, to a much lesser extent, in heart and adrenal. The 2.9- and 6.3-kb mRNAs coding for the brain enzyme are coregulated with the development of brain, suggesting the physiological importance of the enzyme in fatty acid metabolism in brain.