Model for mechanism of astrocyte differentiation is shown in figure 4. Further studies are needed to determine the natural ligands of these glycans in the brain and the receptor molecules on astrocytes, and the functional roles of differentiated astrocytes. By this strategy, microsequencing of 2-3 pmol of oligosaccharides has been achieved. The relative intensities of metastable ions due to fragmentation at glycosidic linkages were different among linkage isomers of particular oligosaccharides, demonstrating that PSD analysis can be a valuable tool in determinig glycosidic linkages in carbohydrate structures. By using these techniques, we have determined scores of carbohydrate structures, such as amyloid precursor protein, tau protein, prion protein, prostate-specific antigen.
Nothing is known of the biosynthetic pathway of mammalian O-mannosyl glycans.