Proteoglycans

Proteoglycans

Proteoglycans (/proʊˈtiːoʊˌɡlaɪkənz/) are a major component of the extracellular matrix, the "filler" substance existing between cells in an organism. The term proteoglycan (proteo- meaning protein and -glycan meaning sugar) derives from the fact that they are proteins modified by glycosylation, the addition of glycosaminoglycan (GAG) chains.

Structure

Proteoglycans are composed of a core protein with one or more covalently attached glycosaminoglycan chain(s). These GAG chains are long, linear carbohydrate polymers that are negatively charged under physiological conditions, due to the occurrence of sulfate and uronic acid groups.

Function

Proteoglycans play crucial roles in numerous biological processes, including cell proliferation, cell adhesion, and cell migration. They also contribute to the resilience and elasticity of certain tissues and joints, and are involved in the binding and storage of growth factors, which regulate cell proliferation and differentiation.

Types

There are several types of proteoglycans, including heparan sulfate proteoglycans, chondroitin sulfate proteoglycans, keratan sulfate proteoglycans, and dermatan sulfate proteoglycans. Each type has a unique structure and function, and is found in different tissues and cell types.

Clinical Significance

Abnormalities in proteoglycan structure or function can lead to a variety of diseases, including osteoarthritis, Ehlers-Danlos syndrome, and Marfan syndrome. In addition, proteoglycans are involved in the progression of certain cancers, as they can influence tumor cell growth and metastasis.

See Also

• Glycoprotein
• Extracellular matrix
• Glycosaminoglycan
• Heparan sulfate
• Chondroitin sulfate
• Keratan sulfate
• Dermatan sulfate

External links

• Medical encyclopedia article on Proteoglycans
• Wikipedia's article - Proteoglycans

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