noun, plural: gangliosides
A glycosphingolipid is a glycolipid comprised of a carbohydrate and a sphingolipid -- particularly one that has a sphingosine backbone. The carbohydrate is linked to a sphingolipid by a glycosidic bond. Examples of glycosphingolipids include cerebrosides, gangliosides, globosides, and glycophosphosphingolipids.
A ganglioside is a glycosphingolipid made up of a glycosphingolipid and sialic acid(s). The sialic acid component is linked to the sugar unit. It is similar to cerebroside in terms of chemical composition. A ganglioside, though, has an additional constituent: one or more sialic acid residue(s), i.e. N-acetylneuraminic or N-glycolylneuraminic. Hydrolysis of a ganglioside would thereby yield sphingosine, fatty acid, carbohydrate, and neuraminic acid.
The gangliosides are found mainly in the cell membrane of the nervous tissue. They also occur in cells of spleen and thymus. Nevertheless, they are first isolated from the ganglion cells of the brain in 1942 (thus, the name). In animals, the gangliosides are regarded as the most complex type of glycolipids. The gangliosides are associated with cell signal transduction.
The presence of excess gangliosides may lead to gangliosidosis, Sandhoff disease, or Tay-Sachs disease. Sandhoff disease is a type of lysosomal storage disease that is often caused by a deficiency in beta-hexosaminidases A and B, resulting in the accumulation of glucoside and ganglioside GM2. Tay-Sachs disease is a type of sphingolipidosis that is often caused also by a deficiency in hexosaminidase A resulting in the accumulation of GM2 gangliosides in neurons.