MOLECULAR DIVERSITY OF SPHINGOLIPID SIGNALING

Sphingolipid breakdown products are now being recognized to play a dua l role in cellular signalling, acting as intracellular as well as extr acellular signalling molecules. Both types of action may even be found with one sphingolipid species. The recent demonstration of G protein- coupled receptors with high affinity for sphingosine 1-phosphate and s phingosylphosphorylcholine has been followed by the discovery of sever al novel sphingolipid actions, such as regulation of heart rate, oxida tive burst, neurite retraction or platelet activation. Ligand profiles and concentration-response relationships suggest the existence of put ative sphingolipid receptor subtypes. Against this background, several observations on supposed sphingolipid second messenger actions deserv e a new evaluation. (C) 1997 Federation of European Biochemical Societ ies.