A Substrate- and Position-specific Acylation of sn-Glycerol 3-Phosphate by Rat Liver Mitochondria

Abstract

Abstract The major products of the acyl-CoA-sn-glycerol 3-phosphate acyltransferase system of rat liver mitochondria were identified as mono- and diacyl-sn-glycerol 3-phosphate. The monoacyl derivative was demonstrated to be a precursor of the diacyl compound. Pronounced substrate and positional specificity during the acylation of sn-glycerol 3-phosphate has been shown. Palmitic acid was found esterified exclusively in position 1 of the sn-glycerol molecule. Oleyl- and linoleyl-CoA failed to show significant activity as donors in the acylation of sn-glycerol 3-phosphate but linoleyl-CoA competes effectively with palmityl-CoA in the acylation of 1-palmityl-sn-glycerol 3-phosphate. Additional experiments distinguished the mitochondrial from the microsomal acylation system and localized the activity in the outer mitochondrial membrane. The combined properties of the mitochondrial acyltransferase system are consistent with the possibility that it may contribute to the asymmetrical distribution of fatty acids found in glycerolipids.