Occurrence of ceramides and neutral glycolipids with unusual long-chain base composition in purified rat liver mitochondria

The free ceramide content of rat liver mitochondria was found to be 1.7 nmol/mg protein and outer membranes contained a three-fold higher concentration than inner membranes. The mitochondrial content in neutral glycolipids was 0.6 nmol/mg protein. The long-chain bases found in free ceramides were d18:I sphingosine, d18:0 3-ketosphinganine and t21:1 phytosphingosine in increasing order. In contrast, 3-ketosphinganine was the only base of glucosglceramide and lactosylceramide of inner membranes, whereas d18:I sphingosine was the major long-chain base of glucosylceramide of outer membranes. (C0) 2001 Federation of European Biochemical Societies, Published by Elsevier Science B.V. All rights reserved.