Sphingosine-based lipids

Sphingosine-based lipids are not present just in the nervous system. They are components of the plasma membranes of most cells and arc involved in regulation of cell gn wth, cell to-ccM adhesion, and transmission of signals from an outside stimulus to the interior of the cell. The study of these lipids has been complicated by the fact that they exist in over 100 forms in mammalian tissues. 

FIGURE 6ill The sphin osine biosyntheiic pathway. As is the case for most biochemical pathways, this pathway utilizes several cofactors that are made from vitamins. The vitamins pantothenic acid, vitamin niacin, and riboflavin are used to make the cofactois iridicaied in the figure. 

Sita of Kttadirnent p Mphoc olinVri Augan bod oligoflBBctiaridSfl 

311b at BRBcTimBnt Qf fpttv acid B oap of ceromidc iairiide faondl 

The most well-known components of the various signaling pathways in the cell include G protein, inositol l,4,5-trisphosphate, cyclic AMR MAP kinase, and protein kinase C, as discussed at various points in this text Sphingosine represents a newcomer to the science of cell signaling. 

Site of attachment of fatty acid group of ceramide (amide bond) 

Sphingosine Long chain fatty ACYL-CoA Coenzyme A 

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Influence of Dietary Fats on Phospholipids in the Body Sphingosine-Based Lipids Covalent Binding of Lipids to Proteins Cholesterol Lipoproteins... 

Structural studies of glycosphingolipids involves determination of the structure of the oligosaccharide chain and of the lipid moiety. For the oligosaccharide chain, it is necessary to determine the composition, molar ratio, and sequence of the monosaccharides, their pyranose or furanose nature, and the position of glycosidic bonds and their configuration for the lipid moiety, the composition of the fatty acids and sphingosine bases must be determined. Used for these purposes are the classical, chemical methods, conventionally accepted in the chemistry of carbohydrates and lipids and based on the degradation of compounds, enzymic, and physicochemical methods, primarily mass spectrometry and n.m.r. spectroscopy. 

From the sea hare Aplysia kurodai, belonging to the subclass Prosobran-chia, two phosphonoglycolipids having complex, carbohydrate chains have also been isolated.143"146 One of the lipids contains one residue each of sphingosine base, fatty acid, glucose, 2-acetamido-2-deoxygalactose, and... 

The lipid composition in all of these oligosylceramides is similar. The major fatty acids are hexadecanoic and octadecanoic acid, and the major sphingosine base is octadeca-4-sphingenine. 

Fatty acids and sphingosines. The lipid composition of the four monosialogangliosides is shown in Table II. The major fatty acids are palmitic, stearic and oleic acids. The long chain base is composed mainly of C-18 sphingosine with less than 20% of dihydrosphingosine. 

The major components of cell membranes are proteins, cholesterol, lipids with a glycerol backbone, and lipids with a sphingosine backbone. The glycerol-based lipids are phospholipids with fatty acids esterified at the 1 and 2 positions of the glycerol, and a molecule of phosphocholine, phosphoethanolamine. 

Karlsson, K.-A. 1970. On the chemistry and occurrence of sphingolipid long-chain bases. Lipids 5 6-43. Goni, F.M., Alonso, A. 2006. Biophysics of sphingolipids. I. Membrane properties of sphingosine, ceramides and other simple sphingolipids. Biochim. Biophys. Acta 1758 1902-1921. 

Sphingophospholipids, 30 see also Sphingolipids Sphingosine bases, 281 Sphingosine, 311 Spinach, 163-65,488 Sponge lipids, 5 Spray reagents, 277 Spreading pressure, 338 Squalene, 138,144,148 Squalus acanthus, 138 Squid, 137... 

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