Structure and biological functions of keratan sulfate proteoglycans.

The skeletal and corneal keratan sulfate proteoglycans show a different metabolic and structural heterogeneity. The domain structure of the carbohydrate chain has been shown to be different in various animal species. There are two major types of skeletal keratan sulfate proteoglycans with and without fucose. The protein cores of the corneal chicken keratan sulfate proteoglycan (lumican) and those of another small keratan sulfate proteoglycan (fibromodulin) have been sequenced. Keratan sulfate oligosaccharides belong to the members of an antigen family of the poly-N-acetyllactosamine series. Monoclonal antibodies and immunoassay procedures for keratan sulfate proteoglycans have been prepared. In osteoarthritis, no significant specific increase of keratan sulfate has been found. Keratan sulfate is a functional substitute for chondroitin sulfate in O2-deficient tissues.