Distribution and characteristics of polysialosyl oligosaccharides in nervous tissue glycoproteins.

Large polysialosyl glycopeptides can be derived from the glycoproteins of both mature as well as early postnatal brain, although their concentration (in terms of sialic acid content) decreases by approximately 75 percent during the first month in rat brain. These glycopeptides were found to contain O-sulfate residues, and subcellular fractionation studies indicated that most of the glycoproteins having polysialosyl units are present in non-synaptic plasma membranes. Large polysialosyl glycopeptides can also be obtained from the membranes of PC12 pheochromocytoma cells, demonstrating that this type of structure is not unique to brain.