Keratan sulfate

Keratan sulfate is a glycosaminoglycan (GAG) found on proteoglycans. It is abundant in the cornea, cartilage, and brain. Keratan sulfate is unique among the GAGs in that it does not contain uronic acid and is not sulfated at the C-5 position of the sugar residue.

Structure

Keratan sulfate consists of a repeating disaccharide unit of galactose and N-acetylglucosamine. The galactose residues can be sulfated at the 6-position and the N-acetylglucosamine residues can be sulfated at the 6-position. The degree of sulfation varies among tissues and species.

Function

Keratan sulfate plays a crucial role in maintaining the transparency of the cornea. It also contributes to the compressive resistance and elasticity of cartilage. In the brain, keratan sulfate is involved in neuronal plasticity and axon guidance.

Clinical significance

Defects in the metabolism of keratan sulfate can lead to a variety of lysosomal storage diseases, including Morquio syndrome and Macular corneal dystrophy. These diseases are characterized by the accumulation of keratan sulfate in tissues and organs, leading to a range of symptoms such as skeletal abnormalities, corneal clouding, and cognitive impairment.

See also

• Glycosaminoglycan
• Proteoglycan
• Morquio syndrome
• Macular corneal dystrophy