Sphingolipid-to-glycerophospholipid conversion in SPL-null cells implies the existence of an alternative isozyme.

Abstract Sphingosine-1-phosphate (S1P) lyase catalyzes the cleavage of the bioactive lipid molecule S1P to phosphoethanolamine and hexadecenal, both of which are utilized as glycerophospholipid precursors. Until now, only one gene, SPL , has been identified as encoding a S1P lyase. In the present study, SPL -null F9 cells were able to convert radiolabeled dihydrosphingosine to glycerophospholipids, albeit at much lower efficiency than parent cells. Lysates prepared from the SPL -null cells exhibited weak but significant dihydrosphingosine-1-phosphate lyase activity in vitro. These results provide evidence of the existence of an alternative S1P lyase.