Homogeneous Aggregation of the 14-kDa β-Galactoside Specific Vertebrate Lectin Complex with Asialofetuin in Mixed Systems

The galactose-specific 14-kDa family of animals lectins are an evolutionary conserved group of proteins that have been implicated in a wide variety of biological processes including cell proliferation, adhesion, and transformation. The present study demonstrates that the dimeric 14-kDa calf spleen lectin forms homogeneous aggregated cross-linked complexes with asialofetuin, a glycoprotein with multiple carbohydrate chains possessing terminal galactose residues, in the presence of other lectins with similar specificities and cross-linking activities. Several galactose-specific plant lectins also form homogeneous aggregated cross-linked complexes with ASF. These results demonstrate a new source of specificity for the 14-kDa family of vertebrate lectins, namely, the ability to selectively cross-link and aggregate glycoproteins in mixed systems. The results have important biological implications for the interactions of multivalent lectins and glycoconjugates, as well as the thermodynamic interactions of multivalent molecules in general.