galactocerebrosides

Galactocerebrosides are a class of glycosphingolipids in which a galactose molecule is attached to a ceramide backbone. They are neutral glycosphingolipids and are among the most abundant lipid constituents of myelin, especially in the white matter of the central nervous system and in Schwann cells of the peripheral nervous system.

The most common member is galactosylceramide (galactocerebroside, GalCer). A related group consists of sulfated galactocerebrosides, known as sulfatides, which carry a sulfate group on the galactose. Together, GalCer and sulfatides are major glycolipids in myelin and are enriched in oligodendrocyte and Schwann cell membranes.

Biosynthesis occurs in the Golgi apparatus, where ceramide is galactosylated by ceramide galactosyltransferase using UDP-galactose to form GalCer; subsequent sulfation yields sulfatide. Degradation happens in lysosomes via galactocerebrosidase. Deficiency of this enzyme leads to accumulation of galactolipids and psychosine, as seen in Krabbe disease, a severe demyelinating disorder.

Functionally, galactocerebrosides contribute to the stability, organization, and signaling of myelin membranes and may participate in cell recognition processes. Altered metabolism of these lipids is associated with demyelinating conditions, and their distribution serves as a histological marker for myelin-rich tissues.