EXPRESSION AND CHARACTERIZATION OF A CARBOHYDRATE-BINDING FRAGMENT OFRAT AGGRECAN

The COOH-terminal portion of cartilage proteoglycan core protein, aggr ecan, expressed by in vitro translation, binds carbohydrate-containing affinity columns. The in vitro expression approach has been used to d efine the sugar-binding portion of the core protein. The active fragme nt, which corresponds closely to the carbohydrate-recognition domains in the family of Ca2+-dependent (C-type) animal lectins, has been expr essed in bacteria and characterized. The CD spectrum of the domain is very similar to the spectrum of the binding domain of serum mannose-bi nding protein, suggesting that its overall structure probably resemble s the known three-dimensional structure of the mannose-binding domain. The binding specificity of the core protein fragment has been charact erized using a solid-phase assay. The results suggest that the monosac charide-binding site is also similar to that in other C-type carbohydr ate-recognition domains.