Ceramide biosynthesis

Ceramide, the lipid carrier of glycosphingolipids, is synthesized de novo in the ER by condensation of palmitoyl-CoA with serine, followed by reduction to dihydrosphingosine, which is acylated to form dihydroceramide. Ceramide is then obtained by introduction of a double bond catalyzed by a specific desaturase enzyme. Ceramide is further transported to the Golgi apparatus to be glycosylated.

FIG: CERAMIDE SYNTHESIS

Sphingosine was named after the Sphinx by the biochemist Johann Thudichum around 1884, who was a fan of Greek mythology. He apparently chose this name because he was puzzled by the complexity of the sphingosine-based structures isolated from brain tissue. Ceramide is the backbone of glycosphingolipids and sphingomyelin, which is a main constituent of myelin sheath in the nervous system. Whereas sphingomyelin carries a phosphocholine group, glycosphingolipids are elongated by different core glycan structures, defining various subclasses found in fungi, plants or animals.

FIG: LIPID BACKBONES