Role of glycosphingolipids in formation and function of membrane microdomains

Recent years have been characterized by a huge interest in the structure and function of mammalian cell membrane lipid domains. The interest in this subject grew further, when their participation in important membrane-associated events such as signal transmission, cell adhesion and lipid/protein sorting was postulated. A common feature of cell membrane domains is their peculiar lipid composition, being enriched in glycosphingolipids, sphingomyelin and cholesterol. A series of theoretical considerations and several experimental data suggest that glycosphingolipids play an important role in the formation and function of membrane domains. Within this review, the involvement of glycosphingolipids in the biogenesis, structure and function of domains is discussed in light of their strong amphiphilic nature and of their peculiar chemical features. These features differentiate glycosphingolipids from other lipids in the membrane, allowing either self-interaction or interaction with other membrane components and external ligands. Due to these interactions, glycosphingolipids undergo lateral phase separation, segregation, and therefore form core domains within the membrane; glycosphingolipid domains constitute the nucleation point that allows co-segregation of other lipids and proteins in a complex domain; finally, glycosphingolipids confer dynamic properties on domains, that are essential to the modulation of cell functions.