Carbohydrate specificity of chicken and human tandem-repeat-type galectins-8 in composition of cells

The network of adhesion/growth-regulatory galectins in chicken (chicken galectin, CG) has only one tandemrepeat-type protein, CG8. Using a cell-based assay and probing galectin reactivity with a panel of fluorescent neoglycoconjugates (glycoprobes), its glycan-binding profile was determined. For internal validation, human galectin-8 (HG8) was tested. In comparison to HG8, CG8 showed a rather similar specificity: both galectins displayed high affinity to blood group ABH antigens as well as to 3'-sialylated and 3'-sulfated lactosamine chains. The most remarkable difference was found to be an ability of HG8 (but not CG8) to bind the disaccharide Gal beta 1-3GlcNAc (Le(c)) as well as branched and linear oligolactosamines. The glycan-binding profile was shown to be influenced by glycocalix of the cell, where the galectin is anchored. Particularly, glycosidase treatment of galectin-loaded cells led to the change of the profile. Thus, we suppose the involvement of cis-glycans in the interaction of cell-anchored galectins with external glycoconjugates.