title: High-affinity binding of recombinant human galectin-4 to SO(3)(-)-->3Galbeta1-->3GalNAc pyranoside.
abstract: Galectin-4 is a member of galectin family and has two carbohydrate recognition domains. Although galectin-4 has been thought to function in cell adhesion, its precise carbohydrate binding specificity has not yet been clarified. We studied the carbohydrate binding specificity of galectin-4 comparatively with that of galectin-3, using surface plasmon resonance, galectin-3- or -4-Sepharose column chromatography and the inhibition assay of their binding to immobilized asialofetuin. Galectin-3 broadly recognized lactose, type 1, type 2, and core 1. The substitution at the C-2 and C-3 position of beta-galactose in these oligosaccharides with alpha-fucose, alpha-GalNAc, alpha-Neu5Ac, or sulfate increased the binding ability for galectin-3, whereas the substitution at the C-4 or C-6 position diminished the affinity. In contrast, galectin-4 had quite weak affinity to lactose, type 1, and type 2 (K(d) congruent with 8 x 10(-4) M). Galectin-4 showed weak binding ability to core 1 and C-2' or -3'-substituted lactose, type 1, and type 2 with alpha-fucose, alpha-GalNAc, or sulfate (K(d) : 5 x 10(-5) approximately 3 x 10(-4) M). Interestingly, the K(d) value, 3.4 x 10(-6) M, of SO(3)(-)-->3Galbeta1-->3GalNAc-O-Bn to galectin-4 at 25 degrees C was two orders of magnitude lower than that of core 1-O-Bn. 3'-Sialylated core 1 had very weak affinity to galectin-4, suggesting that 3'-O-sulfation of core 1 is critical for the recognition. These results suggest that galectin-4 has a unique carbohydrate binding specificity and interacts with O-linked sulfoglycans.
authors.affiliation: CREST (Core Research for Evolutional Science and Technology) of the Japan Science and Technology Corporation, 2-3, Kanda-Surugadai, Chiyoda-ku, Tokyo 101-0062, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Ideo
authors.forename: Akira
authors.initials: A
authors.lastname: Seko
authors.forename: Takashi
authors.initials: T
authors.lastname: Ohkura
authors.forename: Khushi L
authors.initials: KL
authors.lastname: Matta
authors.forename: Katsuko
authors.initials: K
authors.lastname: Yamashita
mesh_terms: D000943:Antigens, Differentiation / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D037502:Galectin 3; D037541:Galectin 4; D006023:Glycoproteins / Q000737:chemistry / Q000378:metabolism; D006388:Hemagglutinins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D037102:Lectins / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D020349:Surface Plasmon Resonance
chemical_list: D000943:Antigens, Differentiation; D037502:Galectin 3; D037541:Galectin 4; D006023:Glycoproteins; D006388:Hemagglutinins; D037102:Lectins; D009844:Oligosaccharides; D011994:Recombinant Proteins