The structures of the asparagine-linked sugar chains of bovine interphotoreceptor retinol-binding protein. Occurrence of fucosylated hybrid-type oligosaccharides.
The sugar chains of interphotoreceptor retinol-binding protein purified from the interphotoreceptor matrix of bovine eyes were liberated from the polypeptide portion by hydrazinolysis followed by N-acetylation and NaB[3H]4 reduction. The oligosaccharide fraction thus obtained was separated into four acidic fractions by paper electrophoresis. The four acidic fractions were confirmed to be mixtures of mono-, di-, tri-, and tetrasialyloligosaccharides. Both N-acetyl- and N-glycolylneuraminic acids were found as sialic acids of interphotoreceptor retinol-binding protein. The monosialylated oligosaccharide fraction, which accounted for 40 molar per cent of the total oligosaccharides liberated, was a mixture of the following hybrid-type oligosaccharides: (Formula: see text) This is the first time that fucosylated hybrid-type oligosaccharides have been found in any glycoprotein. The di-, tri-, and tetrasialyloligosaccharide fractions were composed of biantennary complex-type oligosaccharides, the outer chains of which are either Sia alpha 2----(3- or 6-linked)Gal beta 1----3(Sia alpha 2----6)GlcNac or Sia alpha 2----(3- or 6-linked)Gal beta 1----4GlcNAc.
D000818:Animals; D001216:Asparagine; D002240:Carbohydrate Sequence; D002417:Cattle; D009844:Oligosaccharides / Q000032:analysis*; D010786:Photoreceptor Cells / Q000032:analysis*; D012177:Retinol-Binding Proteins / Q000032:analysis*
D009844:Oligosaccharides; D012177:Retinol-Binding Proteins; D001216:Asparagine