Carbohydrates, Lipids, and Other Natural Products
Carbohydrate Recognition by a Natural Killer Cell Receptor, Ly-49C (∗)

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Ly-49 represents a family of type II transmembrane proteins containing C-type lectin domains. At least two members of the Ly-49 family, namely Ly-49A and Ly-49C, are expressed by distinct subsets of natural killer cells and bind to class I major histocompatibility complex antigens on the surface of target cells. In this report we have established that Ly-49C mediates carbohydrate recognition. The sulfated glycans fucoidan, λ-carrageenan, and dextran sulfate were found to be potent inhibitors of Ly-49C-mediated cell adhesion, whereas other polysaccharides of similar size, charge, or sulfate content were noninhibitory. All of the polysaccharides which inhibited Ly-49C adhesion also blocked the binding of the antibody 5E6 to Ly-49C-expressing COS cells, confirming the direct protein-carbohydrate interaction. The enzymatic removal of specific carbohydrates from the target cell surface has shown that Ly-49C-mediated adhesion is not sialic acid-dependent, but is significantly decreased following fucosidase treatment. These results suggest an important role for carbohydrate recognition by natural killer cell receptors.

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∗

This work was supported by a joint grant from the Cancer Research Society of Canada (to F. T. and D. M.), with core support provided by the British Columbia Cancer Agency. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

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Current address: The British Columbia Institute for Child and Family Health, Division of Infectious and Immunological Diseases, 950 West 28th Ave., Vancouver, British Columbia V5Z 4H4, Canada.

© 1995 ASBMB. Currently published by Elsevier Inc; originally published by American Society for Biochemistry and Molecular Biology.