Sphingolipider

Sphingolipider, the plural form of sphingolipid in several European languages, refers to a diverse class of lipids that share a backbone built on sphingosine, an amino alcohol. They are essential components of cell membranes and play important roles in signaling and recognition processes.

The core of a sphingolipid is ceramide, formed when a fatty acid is amide-linked to sphingosine. Ceramides can be further modified to produce distinct classes: sphingomyelins, which contain a phosphocholine or phosphoethanolamine head group; and glycosphingolipids, which are glycosylated ceramides. Glycosphingolipids are subdivided into cerebrosides (one sugar), globosides (multiple sugars), and gangliosides (sugar chains that include sialic acid). The diverse head groups determine their specific functions in membranes and signaling.

Biosynthesis begins with the de novo formation of ceramide in the endoplasmic reticulum, involving serine palmitoyltransferase and subsequent enzymes that elongate and desaturate the molecule. Ceramide serves as a central hub, branching into sphingomyelin synthesis in the Golgi apparatus or the initiation of glycosphingolipid pathways. Sphingolipid turnover is tightly regulated, enabling rapid adjustments in membrane properties and signaling networks.

Functions of sphingolipider include maintaining membrane structure, forming lipid rafts that organize signaling molecules, and modulating processes such as cell growth, differentiation, and apoptosis. In the nervous system, sphingolipids are particularly abundant and important for myelin and neuronal signaling. Abnormal sphingolipid metabolism is associated with several lysosomal storage diseases, including Gaucher disease, Tay-Sachs disease, and Niemann–Pick disease, as well as broader neurodegenerative and metabolic disorders.

Overall, sphingolipider constitute a structurally and functionally diverse lipid family central to membrane biology and cellular signaling.