29 Jul 2011

Glycoconjugates as well as Membrane Carbohydrates

Tissue recognize one another due to the saccharides attached to cell areas.
They're present generally since oligosaccharides associated through covalent links to lipids and/or protein developing Glycoconjugates. The actual lipid or protein part is integrated into the cell membrane layer structure, using the saccharide part towards the external membrane surface.
Membrane carbohydrates (2-10% of the membranes) are on the extracellular surface bounded to lipids or proteins from the membrane, forming glycoconjugates that serve as docking sites in cell recognition, adhesion and receptor action. These types of sugars include primarily glucose, galactose, mannose, fucose, N-acetyl galactosamine and N-acetyl glucosamine.
The different types of Glycoconjugates include

Type of glycoconjugates
Sugar string + protein = glycoprotein
Sugar string + lipid = glycolipid
Extremely long sugar chains (glycosaminoglycan) + protein = proteoglycan

 In the Proteoglycans, the Glucosaminoglycan moety types the greater fraction of the molecule (tipically a proteoglycan consists of 95 % of carbohydrates) and is the main site of biological activity, supplying several binding sites. They're discovered mostly in the extracellular matrix. They are major components of connective cells.
Membrane layer bound glycoproteins take part in a wide range of cellular phenomena, including cell recognition, cell surface area antigenicity, etc. In the glycoproteins, the majority of the molecule consist of proteins; they have one or more oligosaccharides mounted on the protein, and they are definitely branched and do not possess serial repeats, so they tend to be rich in information, developing highly specific sites for recognition and higher affinity binding through additional proteins
tend to be membrane lipids where the hydrophilic head organizations tend to be oligosaccharides.

As in glycoproteins, glycolipids act as particular sites with regard to recognition by carbohydrate holding proteins. The actual four kinds of human RBC have different oligosaccharides (antigens) in their cell membranes. Blood groups depends on the gangliosides (a type of sphingolipid) in the surface of the RBC .

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