Ganglioside

Gangliosides are usually water-insoluble lipids from the group glycosphingolipids and the glycosides that are found in the outer half of the cell membrane of nearly all vertebrates; particularly the membranes of nerve cells are rich in gangliosides. The name derives from " ganglion " ( nerve nodes ') and the suffix "- osid " (from, glycoside ').

Gangliosides are anchored by their lipid-soluble fraction in the outer cell membrane. Your basic structural skeleton is formed from sphingosine Aminodialkohol. Gangliosides contain roughly shown a complex oligosaccharide, a long chain fatty acid and sphingosine backbone.

In contrast to cerebrosides is complex sphingolipids which have branched sugar chains with up to seven sugar moieties. By this outwardly sugar residues, in particular by the negatively charged sialic acids, is set with the features of the cell surface.

Occurrence

The highest concentrations of gangliosides are found in the nervous system, especially in the gray matter of the brain, where they account for 6% of all lipids. In the nervous system, a variety of gangliosides enriched whose composition in the course of development and adaptation to changing environmental conditions such as fluctuating temperatures changed.

Medical benefits

In addition to the postulated role in the neural information transmission and storage gangliosides also important tumor marker Represents the occurrence of gangliosides in many cancer also suggests a role of glycolipids in the progression of tumor diseases with. Which molecular mechanisms gangliosides act, however, is still unclear.

Blood group

Based on certain gangliosides can determine the blood type. At the sphingosine backbone depends a fatty acid as with any sphingolipid. The specificity of gangliosides are the complex oligosaccharides that are linked to the oxygen atom. Depending on which combination is linked from monosaccharides, determines the blood group. The combination of glucose (Glc ) - galactose (Gal) - N- acetylgalactosamine ( GalNAc ) - galactose - fucose ( Fuc ) encodes for example, for blood group 0 is connected to the chain yet another N- acetylgalactosamine attached, it encodes the blood group A If instead a more galactose attached -. for blood group B.

Schematic representation of the ganglioside blood group A.

Schematic representation of the ganglioside blood group B.

Degradation and pathology

The Gangliosidabbau takes place in the lysosomes. He carried out by highly specific glycosyl hydrolases that sequentially cleave the terminal sugar residues. The GM1 ganglioside is the Stammgangliosid as intermediates generated during the degradation GM2 and GM3 ganglioside. Disorders of Gangliosidabbaus can cause serious diseases ( lysosomal storage diseases), run the sphingolipidoses. The conditional by the β -galactosidase deficiency accumulation of GM1 ganglioside in the central nervous system explains the progressive cerebral symptoms in patients with GM1 gangliosidosis. Hexosaminidase A and B are responsible for the degradation of GM2 ganglioside. Thus ends the defect of hexosaminidase A in the autosomal recessive Tay -Sachs disease, which is accompanied by an increase in the concentration of the ganglioside GM2, untreated before reaching the third year of life deadly. However, by amniocentesis and examination of amniotic fluid on beta -N- Acetylhexosaminidaseaktivität the Tay -Sachs disease can already be diagnosed during fetal development. A deficiency of α -galactosidase A causes an accumulation of globotriaosylceramide, whereby the Fabry disease is caused.