Glycosphingolipids are a subtype of
glycolipids containing the
amino alcohol sphingosine. They may be considered as
sphingolipids with an attached
carbohydrate. Glycosphingolipids are a group of
lipids (more specifically,
sphingolipids) and are a part of the
cell membrane. They consist of a hydrophobic
ceramide part and a
glycosidically bound carbohydrate part. This oligosaccharide content remains on the outside of the cell membrane where it is important for biological processes such as cell adhesion or
cell–cell interactions. Glycosphingolipids play also important role in
oncogenesis and
ontogenesis.
Classification
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. While in gangliosides sialic acids are found, sulfatides have a sulfate group. The structural similarity of most glycolipids is the so-called lactosylceramide, 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:
*
Cerebrosides
*
Gangliosides
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Globosides
Occurrence and function
Gangliosides are mainly found in the cell membranes of the central 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-called
sialyl-Lewis-x
Sialyl LewisX (sLeX), also known as cluster of differentiation 15s (CD15s) or stage-specific embryonic antigen 1 (SSEA-1), is a tetrasaccharide carbohydrate which is usually attached to O-glycans on the surface of cells. It is known to play a vit ...
structure, a tetrasaccharide, which is important for various signal transduction processes. Neutral glycosphingolipids are also important, for example as
blood type
A blood type (also known as a blood group) is a classification of blood, based on the presence and absence of antibodies and inherited antigenic substances on the surface of red blood cells (RBCs). These antigens may be proteins, carbohydrate ...
antigens.
Inheritable enzyme defects can lead to disruption in degradation and therefore to accumulation of glycolipids in various organs. In the case of
cerebrirosis, this affects the cerebrosides (examples are
Gaucher's disease
Gaucher's disease or Gaucher disease () (GD) is a genetic disorder
A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polyg ...
and
Krabbe's disease
Krabbe disease (KD) (also known as globoid cell leukodystrophy or galactosylceramide lipidosis) is a rare and often fatal lysosomal storage disease that results in progressive damage to the nervous system. KD involves dysfunctional metabolism of ...
), in case of
gangliosides it affects the gangliosidoses (e.g.
Tay–Sachs disease) .
See also
*
Sphingomyelin
References
External links
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{{Sphingolipids
Glycolipids