Carbohydrate‐peptide Linkages in Glycoproteins and Mucopolysaccharides From Brain

Abstract

Abstract— Treatment of glycopeptides, prepared from glycoproteins of rat and rabbit brain, with NaOH‐NaBH4 leads to the destruction of a portion of the serine, threonine and galactosamine present, and the appearance in acid hydrolysates of alanine, α‐aminobutyric acid and galactosaminitol. These results indicate that N‐acetylgalactosamine at the reducing end of oligosaccharide chains in brain glycoproteins is linked O‐glycosidically to the hydroxyl groups of serine and threonine residues. 2‐acetamido‐1‐(L‐β‐aspartamido)‐l,2‐dideoxy‐β‐D‐glucose was also detected after partial acid hydrolysis of the alkali‐stable glycopeptides, and most of the carbohydrate in brain glycoproteins appears to be linked by N‐acetylglucosaminylasparagine linkages. The results of the treatment of the sulphated mucopolysaccharides from bovine brain with alkaline‐borohydride indicate that the polysaccharide chains in chondroitin sulphate and heparan sulphate are linked exclusively to serine.

Dolichol‐linked oligosaccharide and glycoprotein biosyntheses in glial cells in primary culture: Development and enzymatic correlates

“…were obtained from Chappel Breeders (St. Louis, MO). Although N-linked glycoproteins (90% of brain Man-P-Do1 was synthesized enzymatically from glycoproteins [Margolis et al, 1972;Margolis and Mar-GDP-['4C]mannose essentially by the method of Waegolis, 19831) have been reported to be involved in such chter and Scher [1981]. The product was purified by SGimportant events in brain development as cell-cell inter-8 1 paper chromatography developed with diisobutyl keactions [Thiery et al, 1977, 19821, neuronal differentia-tone/glacial acetic acid/H20 (60:45:6).…”

Dolichol‐Linked Glycoprotein Synthesis in G1 Is Necessary for DNA Synthesis in Synchronized Primary Cultures of Cerebral Glia

“…The saccharide moiety of N-linked glycoproteins is synthesized while attached to the lipid carrier, dolichyl phosphate, with the latter derived from the sterol biosynthetic pathway (for review, see Lennarz, 1986). Various studies have suggested a relationship between N-linked glycoproteins, which comprise 90% of brain glycoproteins (Margolis et al, 1972;Margolis and Margolis, 1983), and such events in brain development as cellcell recognition (Thiery et al, 1977(Thiery et al, , 1982, neuronal differentiation (Heacock, 1 982;Richter-Landsberg and Duksin, 1983;Yavin et al, 1984), and myelination (Smith and Sternberger, 1982;Smith et al, 1985). Moreover, studies in several nonneural cells have suggested involvement of glycoproteins in cell proliferation (Nishikawa et al, 1980;Omary et al, 1980;Trowbridge and Omary, 1981;Rupar and Cook, 1982;Larsson, 1985;Larsson and Zetterberg, 1986).…”

Specific N-Linked Oligosaccharides Are Required for Oligodendroglial Differentiation but Probably Not for Astrocytic Differentiation

“…The particular importance of N-linked glycoproteins in brain development is demonstrated by the observations that Nlinked glycoproteins comprise 90% of brain glycoproteins, that their deposition increases rapidly with brain development [1,2], and that a variety of important events in brain development (e.g., neuronal differentiation [3][4][5], glial proliferation [6], myelination [7,8]) fail to occur when N-linked glycoprotein synthesis is prevented by tunicamycin. The latter inhibitor blocks the first step of the dolichol-linked pathway of oligosaccharide biosynthesis [9].…”