Keratan sulfate

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Structure of keratan sulfate

Keratan sulfate is a type of glycosaminoglycan (GAG) that is found in various tissues throughout the body, including the cornea, cartilage, and intervertebral discs. It is one of the several types of sulfated GAGs, which are long unbranched polysaccharides consisting of repeating disaccharide units.

Structure

Keratan sulfate is composed of repeating disaccharide units of galactose and N-acetylglucosamine, which are sulfated at various positions. The degree of sulfation and the specific pattern of sulfation can vary, leading to different forms of keratan sulfate. This variability in structure can affect its biological function and interaction with other molecules.

Function

Keratan sulfate plays a crucial role in maintaining the structural integrity and function of various tissues. In the cornea, it contributes to transparency and refractive properties. In cartilage, it is involved in providing resistance to compressive forces, working alongside other components such as chondroitin sulfate and collagen.

Biosynthesis

The biosynthesis of keratan sulfate involves the sequential addition of sugar residues to a core protein, forming a proteoglycan. This process occurs in the Golgi apparatus and involves several glycosyltransferases and sulfotransferases. The core protein is initially synthesized in the endoplasmic reticulum and then transported to the Golgi apparatus for glycosylation.

Clinical Significance

Abnormalities in keratan sulfate metabolism can lead to various disorders. For example, Morquio syndrome (Mucopolysaccharidosis IV) is a genetic disorder characterized by the accumulation of keratan sulfate due to a deficiency in the enzyme required for its degradation. This leads to skeletal abnormalities, vision problems, and other systemic issues.

Related Pages

• Glycosaminoglycan
• Proteoglycan
• Chondroitin sulfate
• Morquio syndrome