ABSTRACT
Sphingolipids are known to function as structural components in cell membranes, but they also have signalling properties. Sphingosine 1-phosphate (S1P), in particular, is an extracellular messenger that activates five G protein-coupled cell surface receptors, and regulates important physiological functions in the cardiovascular and immune system, in hearing, and fertility. Tight regulation of receptor-available S1P, establishment of concentration gradients and the close interplay between S1P and its receptors are necessary requirements in a multitude of processes. Pharmacological and genetic studies in animals have demonstrated that altered S1P concentrations in blood and organs, as well as mutated expression of S1P receptors in certain cell systems can be causative, but may also be efficacious medication in selected diseases. Sphingolipids and their receptors are, therefore, current targets for medical research.