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Homophilic Binding Properties of Galectin‐3: Involvement of the Carbohydrate Recognition Domain
Author(s) -
Kuklinski Stephan,
Probstmeier Rainer
Publication year - 1998
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1998.70020814.x
Subject(s) - galectin , lectin , chemistry , biochemistry , binding domain , galectin 3 , binding site , immunoglobulin domain , biophysics , biology , receptor , immunology
Galectin‐3, an animal lectin specific for β‐galactosides, is composed of three different domains. The N‐terminal half of the molecule (N domain) consists of a short N‐terminal segment followed by glycine‐, proline‐, and tyrosine‐rich tandem repeats. The C‐terminal domain (C domain) harbors the carbohydrate recognition domain homologous to other members of the galectin family of lectins. Galectin‐3 aggregates in solution, and participation of the N domain of the molecule in this process has already been demonstrated. Using a solid‐phase radioligand binding assay, which allows the direct analysis of galectin‐3 self‐association, here we provide evidence that the carbohydrate recognition domain of the lectin is involved in carbohydrate‐dependent homophilic interactions: (a) Radiolabeled galectin‐3 binds to immobilized galectin‐3, and the addition of unlabeled galectin‐3 in solution increases the rate of binding of radiolabeled lectin; (b) binding of radiolabeled galectin‐3 to immobilized galectin‐3 is inhibited by the C domain; (c) binding of radiolabeled galectin‐3 to immobilized galectin‐3 or the C domain is inhibited by lactose but not by sucrose; and (d) the radiolabeled C domain does not bind to immobilized C domain. Taken together, these data suggest that in addition to the N domain, the homophilic interactions of galectin‐3 are mediated by the C domain.