Recognition of complex oligosaccharides by the multi-subunit asialoglycoprotein receptor.

The hepatic asialoglycoprotein receptor, a galactose lectin, is an oligomer of two types of similar polypeptide chains, each of which weakly binds galactose. High-affinity binding of complex oligosaccharides requires a precise geometric arrangement of receptor subunits. The two subunits have different functions in receptor assembly, ligand binding and endocytosis.