Glycosphingolipids are a subtype of

glycolipids Glycolipids are lipids with a carbohydrate attached by a glycosidic (covalent) bond. Their role is to maintain the stability of the cell membrane and to facilitate cellular recognition, which is crucial to the immune response and in the conne ...

containing the

amino alcohol In organic chemistry, alkanolamines are organic compounds that contain both hydroxyl () and amino (, , and ) functional groups on an alkane backbone. The term alkanolamine is a broad class term that is sometimes used as a subclassification. Meth ...

sphingosine Sphingosine (2-amino-4-trans-octadecene-1,3-diol) is an 18-carbon amino alcohol with an unsaturated hydrocarbon chain, which forms a primary part of sphingolipids, a class of cell membrane lipids that include sphingomyelin, an important phos ...

. They may be considered as

sphingolipid Sphingolipids are a class of lipids containing a backbone of sphingoid bases, a set of aliphatic amino alcohols that includes sphingosine. They were discovered in brain extracts in the 1870s and were named after the mythological sphinx because o ...

s with an attached

carbohydrate In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or ma ...

. Glycosphingolipids are a group of

lipid Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include ...

s (more specifically,

s) and are a part of the

cell membrane The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment ( ...

. They consist of a hydrophobic

ceramide Ceramides are a family of waxy lipid molecules. A ceramide is composed of N-acetylsphingosine and a fatty acid. Ceramides are found in high concentrations within the cell membrane of eukaryotic cells, since they are component lipids that make up ...

part and a glycosidically bound

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 interaction Cell–cell interaction refers to the direct interactions between cell surfaces that play a crucial role in the development and function of multicellular organisms. These interactions allow cells to communicate with each other in response to changes ...

s. Glycosphingolipids play also important role in

oncogenesis Carcinogenesis, also called oncogenesis or tumorigenesis, is the formation of a cancer, whereby normal cells are transformed into cancer cells. The process is characterized by changes at the cellular, genetic, and epigenetic levels and abno ...

and

ontogenesis Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the egg to adult. The term can also be used to refer to the st ...

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: *

Cerebroside Cerebrosides is the common name for a group of glycosphingolipids called monoglycosylceramides which are important components in animal muscle and nerve cell membranes. They consist of a ceramide with a single sugar residue at the 1-hydroxyl ...

s *

Ganglioside A ganglioside is a molecule composed of a glycosphingolipid (ceramide and oligosaccharide) with one or more sialic acids (e.g. ''N''-acetylneuraminic acid, NANA) linked on the sugar chain. NeuNAc, an acetylated derivative of the carbohydrate si ...

s *

Globoside Globosides are a sub-class of the lipid class glycosphingolipid with three to nine sugar molecules as the side chain (or R group) of ceramide. The sugars are usually a combination of ''N''-acetylgalactosamine, D-glucose or D-galactose. One ch ...

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 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 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 A ganglioside is a molecule composed of a glycosphingolipid (ceramide and oligosaccharide) with one or more sialic acids (e.g. ''N''-acetylneuraminic acid, NANA) linked on the sugar chain. NeuNAc, an acetylated derivative of the carbohydrate sial ...

it affects the gangliosidoses (e.g.

Tay–Sachs disease Tay–Sachs disease is a genetic disorder 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 around three to six months of age, with the baby ...

) .

References

External links

* {{Sphingolipids Glycolipids

Classification

Occurrence and function

See also

References

External links