Assembly formation of minor dihydrosphingomyelin in sphingomyelin-rich ordered membrane domains.

The lipidome of mammalian cells not only contain sphingomyelin (SM) but also, as a minor component, dihydrosphongomyelin (DHSM), in which the double bond at C4-C5 in the sphingosine base is reduced to a single-bond linkage. It has been indicated that DHSM forms ordered domains more effectively than SM due to its greater potential to induce intermolecular hydrogen bonds. However, direct information on partition and dynamic behaviors of DHSM in raft-like liquid-ordered (L) and non-raft-like liquid-disordered (L) phase-segregated membranes has been lacking.