Gangliosides and Cell Surface Ganglioside Metabolic Enzymes in the Nervous System

Gangliosides are a large group of complex lipids found predominantly in the outer layer of the plasma membrane of cells, particularly abundant in nerve endings. Their half-life in the nervous system is short, and their membrane composition and content are strictly connected to their metabolism. The neobiosynthesis of gangliosides starts in the endoplasmic reticulum and is completed in the Golgi apparatus, whereas catabolism occurs primarily in lysosomes. However, the final content of gangliosides in the plasma membrane is defined by other cellular processes.This chapter will discuss structural changes in the oligosaccharide chains of gangliosides, induced by the activity of plasma membrane-associated glycohydrolases and glycosyltransferases. Some of the plasma membrane enzymes originate from fusion processes between intracellular fractions and the plasma membrane, while, others display a different structure. Several of these plasma membrane enzymes have been characterized and some of them seem to have a specific role in the nervous system.