Figure 1.

Structure of corneal KS-GAGs. Asparagine residues (ASN) within KS-PG core proteins (black) are bound via an N-linkage to two GlcNAc residues (light blue), followed by three mannose residues (orange), which divide the molecule into two arms. The innermost linkage GlcNAc is fucosylated at C6. The elongated (top) and short (bottom) arms both contain repeating GlcNAc and galactose (green) residues linked in –3Galβ1,4GlcNAcβ1– repeating fashion. Whereas these inner disaccharide repeats do not carry sulfate modification, GlcNAc residues in the monosulfated region of the molecule are sulfated at C6. The C6 positions of GlcNAc and most, but not all, galactose residues are modified by sulfate in the disulfated region of KS-GAGs.