Glycosphingolipids
As glycosphingolipids (GSL) refers to a group of lipids (specifically of sphingolipids ), which in the construction of cellular membranes involved. They contain a hydrophobic ceramide component and a glycosidically bound carbohydrate component . This oligosaccharide component is presented on the outside of the cell membrane, where it is important for biological processes such as cell adhesion or cell-cell interactions. Even with the oncogenesis and the ontogeny are glycosphingolipids important.
Classification
In general, two groups of glycosphingolipids can be distinguished: neutral glycosphingolipids, also known as cerebrosides , and negatively charged ones . The latter can be distinguished again on the basis of the load carrier. While sialic acids can be found in gangliosides , sulfatides have a sulfate group. The structural commonality of the majority of all glycolipids is the so-called lactosylceramide, i.e. a lactose disaccharide that is glycosidically bound to a ceramide. Larger structures are divided into different groups based on the sequence and configuration of the sugars they contain, the four most common are the globo, lacto, neoLacto and ganglios series.
Occurrence and function
Gangliosides are found primarily in the cell membranes of the central nervous system , where their carbohydrate group performs tasks in the interaction between individual cells and in signal transmission . But gangliosides are also found in other cells. Sialic acids are here for. B. Part of the so-called sialyl-Lewis-x structure, a tetrasaccharide that is important for various signal transduction processes . Neutral glycosphingolipids are also of biological importance; As the blood group - antigens one.
Hereditary enzyme defects can lead to disruption of the breakdown and storage of glycolipids in various organs. In the case of cerebrosidoses , this concerns the cerebrosides (examples are Gaucher disease and Krabbe's disease ), in the case of gangliosidosis, the gangliosides ( e.g. Tay-Sachs disease ).
literature
- Jeremy M. Berg, John L. Tymoczko, Lubert Stryer : Biochemistry. 6 edition, Spektrum Akademischer Verlag, Heidelberg 2007. ISBN 978-3-8274-1800-5 .
- Donald Voet, Judith G. Voet: Biochemistry. 3rd edition, John Wiley & Sons, New York 2004. ISBN 0-471-19350-X .
- Bruce Alberts , Alexander Johnson, Peter Walter, Julian Lewis, Martin Raff, Keith Roberts: Molecular Biology of the Cell , 5th Edition, Taylor & Francis 2007, ISBN 978-0815341062 .