The long-term aim of these continuing investigations is to correlate the structure, localization, metabolism and functions of nervous tissue glycoconjugates (glycoproteins, proteoglycans and gangliosides) in order to obtain a better understanding of their roles in neural processes. The individual subprojects can be grouped under four specific aims. The first of these is to complete our structural studies on the sulfated glycoprotein-type oligosaccharides present in a previously characterized chondroitin sulfate proteoglycan of brain, and to investigate the biosynthesis of the novel O-glycosidic carbohydrate-peptide linkages involving mannose which we have identified in this proteoglycan. We will also examine the fine structure of the highly complex and variable polysaccharide chains present in several species of heparan sulfate proteoglycans which we have isolated from brain. Our second specific aim is to determine what correlations might exist between the oligosaccharide structure and localization of brain glycoproteins. Oligosaccharide structures will be determined in glycoproteins isolated from brain by use of immunoaffinity procedures employing monoclonal antibodies to potentially interesting glycoprotein antigens. In complementary studies, monoclonal antibodies which rcognize specific structural types of brain glycoprotein oligosaccharides will be generated for use in immunocytochemical studies at the light- and electron microscopic levels, to determine whether there is any apparent pattern in the association of identified glycoprotein oligosaccharide structures with particular morphological features of nervous tissue, or significant changes in localization during brain development. The third specific aim is to characterize the complex carbohydrates of highly purified synaptic vesicles isolated from brain, and of vasopressin- and oxytocin-storing neurosecretory vesicles purified from bovine neurohypophysis. The resulting information, when evaluated together with data from previous studies, will lead to a better understanding of the general role of glycoconjugates in different subcellular organelles having related storage and secretory functions. Finally, we will determine the structures of a series of novel gangliosides which increase approximately 3-fold in response to NGF treatment and axon extension in PC12 pheochromocytoma cells, and will characterize the complex carbohydrates of cultured sympathetic neurons.
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