title: Comparative study of the glycan specificities of cell-bound human tandem-repeat-type galectin-4, -8 and -9.
abstract: 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 following key insights: (i) all three gals bound to oligolactosamines; (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) histo-blood group ABH antigens were the highest affinity ligands in both the cell and the solid-phase assay. Fine specificity differences were revealed as follows: (i) gal-8 and -9, but not gal-4, bound to disaccharide Galβ1-3GlcNAc; (ii) increase in binding due to negatively charged substituents was marked only in the case of gal-4 and (iii) gal-4 and -8 bound preferably to histo-blood group A glycans, whereas gal-9 targeted B-type glycans. Experiments with single carbohydrate recognition domains (CRDs) of gal-4 showed that the C-CRD preferably bound to ABH glycans, whereas the N-CRD associated with oligolactosamines. In summary, the comparative analysis disclosed the characteristic profiles of glycan reactivity for the accessible CRD of cell-bound gals. These results indicate the distinct sets of functionality for these three members of the same subgroup of human gals.
authors.affiliation: Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry RAS, 117997, Miklukho-Maklaya 16/10, Moscow,  Russia.
authors.forename: Olga A
authors.initials: OA
authors.lastname: Vokhmyanina
authors.forename: Eugenia M
authors.initials: EM
authors.lastname: Rapoport
authors.forename: Sabine
authors.initials: S
authors.lastname: André
authors.forename: Vyacheslav V
authors.initials: VV
authors.lastname: Severov
authors.forename: Ivan
authors.initials: I
authors.lastname: Ryzhov
authors.forename: Galina V
authors.initials: GV
authors.lastname: Pazynina
authors.forename: Elena
authors.initials: E
authors.lastname: Korchagina
authors.forename: Hans-J
authors.initials: HJ
authors.lastname: Gabius
authors.forename: Nicolai V
authors.initials: NV
authors.lastname: Bovin
mesh_terms: D000017:ABO Blood-Group System / Q000737:chemistry / Q000378:metabolism; D000606:Amino Sugars / Q000737:chemistry* / Q000378:metabolism; D001402:B-Lymphocytes / Q000737:chemistry* / Q000166:cytology / Q000378:metabolism; D001665:Binding Sites; D001681:Biological Assay; D002240:Carbohydrate Sequence; D002460:Cell Line; D005456:Fluorescent Dyes; D037541:Galectin 4 / Q000737:chemistry* / Q000378:metabolism; D037161:Galectins / Q000737:chemistry* / Q000378:metabolism; D006001:Glycoconjugates / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D011134:Polysaccharides / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D055672:Static Electricity
chemical_list: D000017:ABO Blood-Group System; D000606:Amino Sugars; D005456:Fluorescent Dyes; D037541:Galectin 4; D037161:Galectins; D006001:Glycoconjugates; C091991:LGALS8 protein, human; C105032:LGALS9 protein, human; D011134:Polysaccharides; D011994:Recombinant Proteins