<biochemistry> A macromolecule found on the surface of eukaryotic cells which is thought to play a role in the cells recognition of other cells or of a substrate. It consists of a network of long, branched chains made up of repeating units of disaccharides which contain amino groups sugars, at least one of which has a negatively charged side group (carboxylate or sulphate).
Commonest are hyaluronate (D glucuronic acid N acetyl D glucosamine: MW up to 10 million), chondroitin sulphate (D glucuronic acid N acetyl D galactosamine 4 or 6 sulphate), dermatan sulphate (D glucuronic acid or L iduronic acid N acetyl D galactosamine), keratan sulphate (D galactose N acetyl D glucosamine sulphate) and heparan sulphate (D glucuronic acid or L iduronic acid N acetyl D glucosamine).
Glycosaminoglycan side chains (with the exception of hyaluronate) are covalently attached to a core protein at about every 12 amino acid residues to produce a proteoglycan, these proteoglycans are then noncovalently attached by link proteins to hyaluronate, forming an enormous hydrated space filling polymer found in extracellular matrix. The extent of sulphation is variable and the structure allows tremendous diversity.
(14 Oct 1997)
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