A novel monoantennary complex-type sugar chain found in octopus rhodopsin: occurrence of the Gal beta1-->4Fuc group linked to the proximal N-acetylglucosamine residue of the trimannosyl core.

The N-linked sugar chains were liberated as oligosaccharides from octopus rhodopsin by hydrazinolysis. Most of the oligosaccharides were neutral, and separated into two major components by column chromatography using immobilized lectins and Bio-Gel P-4. Structural analysis of the one major component by sequential exoglycosidase digestion, chemical fragmentation in combination with methylation analysis revealed that it is a nonasaccharide; Man alpha1-->6(Gal beta1-->3GlcNAc beta1-->2Man alpha1-->3)Man beta1--> 4GlcNAc beta1-->4(Gal beta1-->4Fuc alpha1-->6)GlcNAc. This structure is quite unique in that a novel galactosylated fucose residue is attached to the reducing terminal N-acetylglucosamine residue.