Figure 1

Pathways involved in cellular homeostasis of ceramides: The diagram shows the synthesis of ceramides in the endoplasmic reticulum (ER). This involves de novo synthesis (A), hydrolysis of sphingomyelin at the plasma membrane (B), and delivery of sphingolipids to lysosomes (C) for recycling. From the ER, ceramides are transported to the Golgi by ceramide transport protein (CERT) and converted to different sphingolipids. These sphingolipids are then transported to the plasma membrane (PM), to plasma, and and to lysosomes. Various mechanisms involved in the transport of ceramides and sphingolipids in different subcellular compartments are discussed in the review. Cer-1P, ceramide 1 phosphate; CPE, ceramide phosphoethanolamine; SMS, sphingomyelin synthase; Galcer, galactosylceramide; Glucer, glucosylceramide; LacCer, lactosylceramide; GM3, ganglioside GM3.