Cytidine-5′-diphosphate-1,2-diacyl-sn-glycerol Import into Mitochondria through Mitochondrial Membrane Contact Sites in Permeabilized Rat Liver Hepatocytes

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The location of cytidine-5′-diphosphate-1,2-diacyl-sn-glycerol import into mitochondria was examined in permeabilized rat liver hepatocytes. The model utilized the ability of intact mitochondria to freely import [14C]glycerol-3-phosphate. Import of cytidine-5′-diphosphate-1,2-diacyl-sn-glycerol was measured by the synthesis of phosphatidyl[14C]glycerol. Phosphatidyl [14C]glycerol was synthesized in a time- and concentration-dependent manner in the presence of cytidine-5′-diphosphate-1,2-diacyl-sn-glycerol. The presence of ATP in the incubations stimulated phosphatidyl[14C]glycerol formation. The presence of adriamycin, at concentrations that block import of proteins into mitochondria, inhibited the formation of phosphatidyl [14C]glycerol. In addition, adriamycin inhibitedin vitrobiosynthesis of phosphatidyl[14C]glycerol in mitochondrial but not microsomal fractions. 1,4-Dinitrophenol, which may decrease the number of mitochondrial inner and outer membrane contact sites, inhibited formation of phosphatidyl[14C]glycerol in permeabilized hepatocytes. The results demonstrate that cytidine-5′-diphosphate-1,2-diacyl-sn-glycerol may be imported into mitochondria through inner and outer mitochondrial membrane contact sites in hepatocytes.