The occurrence of GM4 and GM2 in erythrocytes from inbred strains of mice.

Glycolipids of erythrocytes from inbred mice, C3H/He and CDF1, were analyzed. Galactosylceramide, glucosylceramide, GM4 and GM2 were separated and their structures were established. Sialic acid of GM4 was exclusively N-acetylneuraminic acid, while GM2 contained only N-glycolylneuraminic acid. The fatty acid composition of GM4 was very similar to that of galactosylceramide, and a similarity was also found between that of GM2 and glucosylceramide. These results suggest that erythroid cells of mice have two separate biosynthetic pathways of gangliosides. One is the pathway to GM4 (NeuAc) from galactosylceramide, and the other is that for synthesizing GM2 (NeuGc) from glucosylceramide.