The asparagine-linked sugar chains of the glycoproteins in calf thymocyte plasma membrane. Structural studies of acidic oligosaccharides.

The acidic oligosaccharide fraction obtained by paper electrophoresis of the hydrazinolysate of the plasma membrane glycoprotein mixture of calf thymocytes was fractionated by high voltage paper electrophoresis into 15 acidic components. Three of them were mixtures of two acidic oligosaccharides, while the remaining 12 were almost pure acidic oligosaccharides. The 18 oligosaccharides have a common core hexasaccharide, Man alpha 1 yields 6(man beta 1 yields 3)Man beta 1 yields 4GlcNAc beta 1 yields 4(Fuc alpha 1 yields 6)GlcNAc. The number of outer chains ranges from two to four. Three different types of outer chains, Gal beta 1 yields 4 GlcNAc beta 1 yields, Gal beta 1 yields 3 GlcNAc beta 1 yields, and Gal beta 1 yields 4 GlcNAc beta 1 yields 3Gal beta 1 yields 4GlcNAc beta 1 yields, were found to occur in the acidic oligosaccharides in various combination. In the biantennary oligosaccharides, the two outer chains are linked only at the C-2 position of the two alpha-mannosyl residues of the core hexasaccharide. All triantennary oligosaccharides have an additional outer chain at the C-4 position of the alpha-mannosyl residue constructing the Man alpha 1 yields 6Man group of the core. Two outer chains of tetraantennary oligosaccharides are linked at the C-2 and 4 positions of one alpha-mannosyl residue and the remaining two outer chains at the C-2 and 6 positions of the other alpha-mannosyl residue of the core. An interesting observation is that C-2,6 disubstitution always occurs on the alpha-mannosyl residue of the Man alpha 1 yields 6 side in all oligosaccharides with Gal beta 1 yields 4GlcNAc beta 1 yields 3Gal beta 1 yields 4GlcNAc beta 1 yields outer chain, while in other tetraantennary oligosaccharides, C-2,6 disubstitution always occurs on the alpha-mannosyl residue of the Man alpha 1 yields 3 side. No sialylated Gal beta 1 yields 3Gal beta 1 yields 4GlcNAc beta 1 yields outer chain was found in the acidic oligosaccharides studied in this paper.