Glycosphingolipids in Secondary Lysosomes Prepared from Rat Liver

Glycosphingolipid classes were isolated from unfractionated liver and from the buoyant fraction of secondary lysosomes following pretreatment of rats with Triton WR-1339. They were identified by thin-layer chromatography and by sugar analysis using gas chromatography and were quantified by estimating long chain base. Hematoside containing N-acetyl neuraminic acid, glucosyl, lactosyl, trihexosyl, and galactosamine-containing tetrahexosyl ceramides were identified in unfractionated liver in the following concentrations, respectively: 0.89, 0.59, 0.19, 0.06, and 0.1 nmol/mg protein. The same glycosphingolipid classes were identified in buoyant Triton-filled lysosomes where their respective concentrations in terms of protein were 8.6, 21, 28, 34, and 28 times as great as in unfractionated liver. The lysosome fraction was enriched 28-fold in acid phosphatase. These results demonstrate that some glycosphingolipid classes are concentrated in secondary lysosomes to a degree expected of markers for primary lysosomes and plasma membrane. Secondary lysosomes are thought to be derived from these latter two structures.