GANGLIOSIDE GM2 IS SUBSTRATE FOR A SIALIDASE IN MDCK CELLS

GM1 ganglioside carrying a fluorescent fatty acid in substitution of t he natural one, has been administered to cultured Madin-Darby canine k idney (MDCK) cells for different pulse times (0.5-24 h), and its metab olic fate was followed. The fluorescent GM2, asialo-GM2, asialo-GM1 an d ceramide were the only detectable metabolites. The complete absence of fluorescent GM3 is consistent with the presence in these cells of a sialidase working on GM1 and GM2 gangliosides. After treatment of the cells with chloroquine the fluorescent CMI remained essentially undeg raded, indicating a catabolic processing at lysosomal level. (C) 1998 Federation of European Biochemical Societies.