The activity of GD3 synthase modulates the ganglioside pattern in rat liver

Variations of the ganglioside composition in the livers of Wistar rats correlated with the activity of GD3 synthase in the corresponding liver homogenates. With increasing enzyme activity, higher proportions of b-series gangliosides (GD3, GD1b, GT1b) were detected. No significant changes in the activity of GM2 synthase or GM1 synthase were observed, indicating a regulatory function for GD3 synthase in this tissue. Young animals showed an average GD3 synthase activity of 0.5-0.6 nmol.h-1.mg protein-1 without sex-dependent variations. Among the older animals, however, males expressed an activity five-fold higher than females, suggesting that this enzyme might be affected by hormones.