Glycosaminoglycan biosynthesis - keratan sulfate - Ficedula albicollis (collared flycatcher)

Keratan sulfate (KS) is a glycosaminoglycan with the basic disaccharide unit of N-acetyllactosamine, Gal(b1-4)GlcNAc(b1-3), with sulfate esters at C-6 of GlcNAc and Gal residues. There are two types of KS distinguished by the protein linkage: type I for N-linked via the N-glycan core structure and type II for O-linked via the O-glycan core 2 structure.