Structure of Glycoconjugates of Intestinal Mucosal Membranes

The intestinal absorptive cells have functional polarity and are extensively covered by a layer of mucus. The carbohydrate moieties of glycoconjugates have been shown to be involved in many important biological functions including maintenance of the physicochemical properties of the molecule, cellular behavior, and immunological activities. There are two main classes of carbohydrate-containing molecule; glycolipid and glycoprotein. Glycolipids are complex lipids to which carbohydrate side chains are linked and exist predominantly as structural components of the microvillus membranes. Glycoproteins occur as both secretory products and structural components of the membrane. Intestinal mucosal membranes are rich in glycoproteins and glycolipids. Nearly all the proteins in the brush border membranes are glycoproteins and glycolipids constitute about 20% of the total brush border membrane lipid, one of the highest contents of all glycolipid-containing membranes of mammalian cells. Bacterial adhesion was most pronounced in newborn animals, indicating possible differences between the intestinal cell surface glycoconjugates of newborn and adult animals.