Sphingomyelin is a phospholipid present in cell membranes. It has a hydrophilic (polar) head, and a hydrophobic (nonpolar) tail - it is an amphilic molecule.
It is produced from sphingosine, as opposed to glycerol - the backbone of the main phospholipids, making is a sphingolipid.
Sphingosine is composed of a fatty acid chain with two hydroxyl groups and an amino group.
The fatty acid tail in sphingomyelin is attached to an amino group, and a phosphocholine group is attached to the terminal hydroxyl group.
The structure of sphingomyelin leaves one free hydroxyl group on the molecule, which results in the polar characteristics of the hydrophilic head. This means hydrogen bonds can form with nearby lipids, water molecules or other membrane proteins .
- ↑ B. Alberts, A. Johnson, J Lewis at al. (2008) Molecular Biology of the Cell, 5th Edition, New York: Garland Science. Chapter 10, pages 618-619