Figure 1.

The sphingolipid metabolic pathway.

Notes: S1P is generated by the catabolism of ceramide, which is the central molecule of the sphingolipid metabolic pathway. Sphingomyelin is hydrolyzed by sphingomyelinase, yielding phosphorylcholine and ceramide; the latter is further metabolized to form a free fatty acid and sphingosine. Sphingosine can be phosphorylated by sphingosine kinase resulting in S1P. S1P can be dephosphorylated back to sphingosine by S1P phosphatase (or nonspecific lipid phosphatases), or irreversibly cleaved by S1P lyase into phosphoethanolamine and trans-2-hexadecenal.

Abbreviation: S1P, sphingosine-1-phosphate.