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Glycosphingolipids are a subtype ofglycolipids containing theamino alcoholsphingosine. They may be considered assphingolipids with an attachedcarbohydrate. Glycosphingolipids are a group oflipids (more specifically,sphingolipids) and are a part of thecell membrane. They consist of a hydrophobicceramide part and aglycosidically bound carbohydrate part. Thisoligosaccharide content remains on the outside of the cell membrane where it is important for biological processes such as cell adhesion orcell–cell interactions. Glycosphingolipids also play an important role inoncogenesis andontogenesis.
In general, glycosphingolipids can be categorized into two groups: neutral glycosphingolipids (also called glycosphingolipids) and negatively charged glycosphingolipids. The latter can be distinguished again by means of the charge carrier:gangliosides, which havesialic acids; andsulfatides, which have asulfate group. The structural similarity of most glycolipids is the so-calledlactosylceramide, that is, a lactose disaccharide that is glycosidically bound to a ceramide. Larger structures are subdivided into different groups by the sequence and configuration of the sugars, the four most common being globo-, lacto-, neoLacto- and gangliose.
Glycosphingolipids include:[1]
Gangliosides are mainly found in the cell membranes of thecentral nervous system, where their carbohydrate group is responsible for the interaction between individual cells and for signaling. However, gangliosides are also found in other cells. Sialic acids are, for example, part of the so-calledsialyl-Lewis-x structure, a tetrasaccharide, which is important for various signal transduction processes. Neutral glycosphingolipids are also important, for example asblood type antigens.
Inheritable enzyme defects can lead to disruption in degradation and therefore to accumulation of glycolipids in various organs. In the case ofcerebrirosis, this affects the cerebrosides (examples areGaucher's disease andKrabbe's disease); in the case ofgangliosides, it affects the gangliosidoses (e.g.Tay–Sachs disease).