Fig. 1

Common structures of representative SLs. SLs contain a long-chain base whether sphinganine (saturated) or sphingosine (monounsaturated at C4). N-acylation at the amino group on C2 creates ceramide, which may consist of varying number of carbon atoms. The representative ceramide shown here is palmitoyl-ceramide that contains 16 carbons. The addition of a phosphocholine at C1 creates the parent phosphosphingolipid sphingomyelin, and glycosylation at the same carbon generates glucosylceramide