THE CERAMIDE STRUCTURE OF GM1 GANGLIOSIDE DIFFERENTLY AFFECTS ITS RECOVERY IN LOW-DENSITY MEMBRANE FRACTIONS PREPARED FROM HL-60 CELLS WITH OR WITHOUT TRITON-X100

Gangliosides are characteristically enriched in various membrane domains that can be isolated as low density membrane fraction insoluble in detergents (detergent-resistant membranes, DRMs) or obtained after homogenization and sonication in 0.5 M sodium carbonate (low-density membranes, LDMs). We assessed the effect of the ceramide structure of four [3H]-labeled GM1 ganglioside molecular species (GM1s) taken up by HL-60 cells on their occurrence in LDMs, and compared it with our previous observations for DRMs. All GM1s contained C18 sphingosine, which was acetylated in GM1(18:1/2) or acylated with C14, C18 or C18:1 fatty acids (Fas)