Glycosphingolipids are a subtype of
glycolipids containing the
amino alcohol sphingosine. They may be considered as
sphingolipid
Sphingolipids are a class of lipids containing a backbone of sphingoid bases, which are a set of aliphatic amino alcohols that includes sphingosine. They were discovered in brain extracts in the 1870s and were named after the mythological sp ...
s with an attached
carbohydrate
A carbohydrate () is a biomolecule composed of carbon (C), hydrogen (H), and oxygen (O) atoms. The typical hydrogen-to-oxygen atomic ratio is 2:1, analogous to that of water, and is represented by the empirical formula (where ''m'' and ''n'' ...
. Glycosphingolipids are a group of
lipid
Lipids are a broad group of organic compounds which include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include storing ...
s (more specifically,
sphingolipid
Sphingolipids are a class of lipids containing a backbone of sphingoid bases, which are a set of aliphatic amino alcohols that includes sphingosine. They were discovered in brain extracts in the 1870s and were named after the mythological sp ...
s) and are a part of the
cell membrane
The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extr ...
. They consist of a hydrophobic
ceramide
Ceramides are a family of waxy lipid molecules. A ceramide is composed of sphingosine and a fatty acid joined by an amide bond. Ceramides are found in high concentrations within the cell membrane of Eukaryote, eukaryotic cells, since they are co ...
part and a
glycosidically bound carbohydrate
A carbohydrate () is a biomolecule composed of carbon (C), hydrogen (H), and oxygen (O) atoms. The typical hydrogen-to-oxygen atomic ratio is 2:1, analogous to that of water, and is represented by the empirical formula (where ''m'' and ''n'' ...
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 also play an 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
*
Ganglioside
A ganglioside is a molecule composed of a glycosphingolipid (ceramide and oligosaccharide) with one or more sialic acids (e.g. N-acetylneuraminic acid, ''N''-acetylneuraminic acid, NANA) linked on the sugar chain. NeuNAc, an acetylated derivative ...
s
*
Globosides
*
Isoglobotriosylceramide
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 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 based on the presence and absence of antibody, antibodies and Heredity, inherited antigenic substances on the surface of red blood cells (RBCs). These antigens may be proteins, carbohydrates, glycop ...
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 in which glucocerebroside (a sphingolipid, also known as glucosylceramide) accumulates in cells and certain organs. The disorder is characterized by bruising, fatigue, anemia, low ...
and
Krabbe's disease); in the case of
gangliosides, it affects the gangliosidoses (e.g.
Tay–Sachs disease
Tay–Sachs disease is an Genetic disorder, inherited fatal lysosomal storage disease that results in the destruction of nerve cells in the brain and spinal cord. The most common form is infantile Tay–Sachs disease, which becomes apparent arou ...
).
See also
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Sphingomyelin
Sphingomyelin (SPH, ) is a type of sphingolipid found in animal cell membranes, especially in the membranous myelin sheath that surrounds some nerve cell axons. It usually consists of phosphocholine and ceramide, or a phosphoethanolamine hea ...
References
External links
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{{Sphingolipids
Glycolipids