Comparative study of the glycan specificities of cell-bound human tandem-repeat-type galectin-4,-8 and-9

Adhesion/growth-regulatory galectins (gals) exert their functionality by the cis/trans-cross-linking of distinct glycans after initial one-point binding. In order to define the specificity of ensuing association events leading to cross-linking, we recently established a cell-based assay using fluorescent glycoconjugates as flow cytometry probes and tested it on two human gals (gal-1 and-3). Here we present a systematic study of tandem-repeat-type gal-4,-8 and-9 loaded on Raji cells resulting in the follow-ing key insights: (i) all three gals bound to oligolactosa-mines; (ii) binding to ligands with Galβ1-3GlcNAc or Galβ1-3GalNAc as basic motifs was commonly better than that to canonical Galβ1-4GlcNAc; (iii) all three gals bound to 3′-O-sulfated and 3′-sialylated disaccharides mentioned above better than that to parental neutral forms and (iv