Glycolipids and Their Classification
Thursday, May 10, 2012
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Introduction:
Glycolipids are membrane components in species which range from bacteria to man especially in those organisms which live in uncommon severe conditions. The most probable function of glycolipids in membrane is based on their capability to go through extensive interlipid hydrogen bonding via glycosyl head groups; therefore they provide architectural reliability to the membranes of the organisms. Besides, being architectural components of the cell membrane, they play a vital role in cellular functions such as in cell-cell communication, as receptor components, as anchors for proteins and as regulators of signal transduction.
Main Idea:
The term glycolipid represents any compound containing one or more monosaccharide residues limited by a glycosidic linkage to a hydrophobic moiety such as an acylglycerol, a sphingoid, a ceramide (N-acylsphingoid) or a prenyl phosphate. Their role is to provide energy and also serve as markers for cellular identification.
Moreover, glycolipids offer a molecular foundation for clustering of signal transducers. The limited relationships between cholesterol and glycolipids in the tissue layer are the power that segregates them from phospholipids that remain liquid in characteristics.
Classification of Glycolopids:
Glycolipids are categorized as follows:
Glycoglycerolipids: The term glycoglycerolipid is used to assign glycolipids containing mono, di or trisaccharides attached glycosidically to the hydroxyl band of diglycerides. Monogalactosyl-diacylglycerols and digalactosyldiacylglycerols are the primary glycolipid elements of the various walls of chloroplasts and also these are the most abundant fats in all photosynthetic cells, such as those of higher plants, plankton and certain bacteria.
Glycosphingolipids:The term glycosphingolipid represents fats containing at least one monosaccharide residue linked to ceramide moiety. Ceramides are amides of fatty acids with long chain di or trihydroxy bases. The acyl group of ceramides is usually a long chain saturated or monounsaturated fatty acids. Glycosphingolipids are subdivided as follows:
Neutral glycosphingolipids: These glycolipids constitute one or more glycosyl moieties that come with ceramide e.g. cerebrosides: Cerebrosides are monoglycosylceramides in which glucose or galactose sugar residue is connected by O-ester linkage to the main alcohol of the ceramide. Galactosylceramides are found in all nervous tissues, but they can amount to 2% of the dry bodyweight of brain and 12% of white matter. Glucosylceramide (Glcs1-1'Cer) is found at low stages in animal tissues, such as spleen and erythrocytes, as well as in nervous tissues.
Oligoglycosylceramides: Glycosphingolipids containing more than one glucose moiety is supposed to be the oligoglycosylceramide group. They are essential components of cellular membranes of most eukaryotic organisms and some viruses. The most essential and abundant of the oligosylceramides is β-D-galactosyl-(1-4)-β-D-glucosyl-(1-1')-ceramide, also known as lactosylceramide (LacCer).
Acidic glycosphingolipids: They are separated into two groups:
Sulfoglycosphingolipids: They are sometimes called as "sulfatides" or "sulfatoglycosphingolipids" also. These are glycosphingolipids holding a sulfate ester group connected to the carbohydrate moiety. Sulfated is mainly produced of 3-sulfate esters of galactosylcerebrosides (galactosyl-3-sulfate esters). They are mainly found in cells that are very dynamic in sodium transport such as kidneys, sodium glands and gills.
Gangliosides: This group of glycosphingolipids comprises of molecules consisting of ceramide connected by a glycosidic bond to an oligosaccharide cycle containing hexose and sialic acid units. These fats can amount to 6% of the body weight of lipids from brain. One of the typical monosialo-gangliosides is ganglioside GM1.
Conclusion:
Glycolipids in the cell membranes play a vital role in recognition and signaling activities in a variety of biological phenomena. Recently, studies regarding the natural features of glycolipids and cell surface microdomains (caveolae, lipid rafts, or glycolipid-enriched microdomains) in stem cells are emerging.
Glycolipids are membrane components in species which range from bacteria to man especially in those organisms which live in uncommon severe conditions. The most probable function of glycolipids in membrane is based on their capability to go through extensive interlipid hydrogen bonding via glycosyl head groups; therefore they provide architectural reliability to the membranes of the organisms. Besides, being architectural components of the cell membrane, they play a vital role in cellular functions such as in cell-cell communication, as receptor components, as anchors for proteins and as regulators of signal transduction.
Main Idea:
The term glycolipid represents any compound containing one or more monosaccharide residues limited by a glycosidic linkage to a hydrophobic moiety such as an acylglycerol, a sphingoid, a ceramide (N-acylsphingoid) or a prenyl phosphate. Their role is to provide energy and also serve as markers for cellular identification.
Moreover, glycolipids offer a molecular foundation for clustering of signal transducers. The limited relationships between cholesterol and glycolipids in the tissue layer are the power that segregates them from phospholipids that remain liquid in characteristics.
Classification of Glycolopids:
Glycolipids are categorized as follows:
Glycoglycerolipids: The term glycoglycerolipid is used to assign glycolipids containing mono, di or trisaccharides attached glycosidically to the hydroxyl band of diglycerides. Monogalactosyl-diacylglycerols and digalactosyldiacylglycerols are the primary glycolipid elements of the various walls of chloroplasts and also these are the most abundant fats in all photosynthetic cells, such as those of higher plants, plankton and certain bacteria.
Glycosphingolipids:The term glycosphingolipid represents fats containing at least one monosaccharide residue linked to ceramide moiety. Ceramides are amides of fatty acids with long chain di or trihydroxy bases. The acyl group of ceramides is usually a long chain saturated or monounsaturated fatty acids. Glycosphingolipids are subdivided as follows:
Neutral glycosphingolipids: These glycolipids constitute one or more glycosyl moieties that come with ceramide e.g. cerebrosides: Cerebrosides are monoglycosylceramides in which glucose or galactose sugar residue is connected by O-ester linkage to the main alcohol of the ceramide. Galactosylceramides are found in all nervous tissues, but they can amount to 2% of the dry bodyweight of brain and 12% of white matter. Glucosylceramide (Glcs1-1'Cer) is found at low stages in animal tissues, such as spleen and erythrocytes, as well as in nervous tissues.
Oligoglycosylceramides: Glycosphingolipids containing more than one glucose moiety is supposed to be the oligoglycosylceramide group. They are essential components of cellular membranes of most eukaryotic organisms and some viruses. The most essential and abundant of the oligosylceramides is β-D-galactosyl-(1-4)-β-D-glucosyl-(1-1')-ceramide, also known as lactosylceramide (LacCer).
Acidic glycosphingolipids: They are separated into two groups:
Sulfoglycosphingolipids: They are sometimes called as "sulfatides" or "sulfatoglycosphingolipids" also. These are glycosphingolipids holding a sulfate ester group connected to the carbohydrate moiety. Sulfated is mainly produced of 3-sulfate esters of galactosylcerebrosides (galactosyl-3-sulfate esters). They are mainly found in cells that are very dynamic in sodium transport such as kidneys, sodium glands and gills.
Gangliosides: This group of glycosphingolipids comprises of molecules consisting of ceramide connected by a glycosidic bond to an oligosaccharide cycle containing hexose and sialic acid units. These fats can amount to 6% of the body weight of lipids from brain. One of the typical monosialo-gangliosides is ganglioside GM1.
Conclusion:
Glycolipids in the cell membranes play a vital role in recognition and signaling activities in a variety of biological phenomena. Recently, studies regarding the natural features of glycolipids and cell surface microdomains (caveolae, lipid rafts, or glycolipid-enriched microdomains) in stem cells are emerging.
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