Receptors for fucose-binding proteins of Lotus tetragonolobus isolated from mouse embryonal carcinoma cells. Structural characteristics of the poly (N-acetyllactosamine)-type glycan

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Abstract
Receptors for fucose-binding proteins of Lotus tetragonolobus were isolated from N4-1 and F9 embryonal carcinoma cells. They were glycorproteins, whose major components had apparent relative molecular masses of more than 100000. Carbohydrates released from the receptors of N4-1 cells by hydrazinolysis were separated into three fractions by gel filtration. Binding activity to the lectin was detected in the high-molecular-mass fraction. The composition of the large glycan was characteristic of the poly(N-acetyllactosamine)-type, and glucosamine wa identified as the sugar involved in the protein-carbohydrate linkage. The glycan has one fucosyl residue per four N-acetyllactosamine units. Most of the fucose was linked to the C-3 hydroxyl group of N-acetylglucosamine. No Fuc.alpha.1 .fwdarw. 2Gal or Fuc.alpha.1 .fwdarw. 4GlcNAc linkage was detected. The glycan had a relative molecular mass of 9000 or more and the poly(N-acetyllactosamine) units were branched. N-Acetylgalactosamine residues were detected in non-reducing ends of at least a part of the glycan. Therefore, the glycan has a more complex structure than the related one from human granulocytes, although both of them have Fuc.alpha.1 .fwdarw. GlcNAc termini.