Xenopus galectin-VIIa binds N-glycans of members of the cortical granule lectin family (xCGL and xCGL2).
We have identified members of the Xenopus cortical granule lectin (xCGL) family as candidate target glycoproteins of Xenopus galectin-VIIa (xgalectin-VIIa) in Xenopus embryos. In addition to the original xCGL, we also identified a novel member of the xCGL family, xCGL2. Expression of the mRNAs of xCGL and xCGL2, as well as that of xgalectin-VIIa, was observed throughout early embryogenesis. Two and three potential N-glycosylation sites were deduced from the amino acid sequences of xCGL and xCGL2, respectively, and xgalectin-VIIa recognizes N-glycans linked to a common site in xCGL and xCGL2 and also recognizes N-glycans linked to a site specific to xCGL2. However, interaction between xgalectin-Ia and xCGLs was not detectable. We also obtained consistent results on surface plasmon resonance analysis involving xCGLs as ligands and xgalectins as analytes. The Kd value of the interaction between xgalectin-VIIa and xCGLs was calculated to be 35.9 nM. The structures of the N-glycans of xCGLs, which were recognized by xgalectin-VIIa, were analyzed by the two-dimensional sugar map method, and three kinds of N-acetyllactosamine type, biantennary N-glycans were identified as the major neutral N-glycans. The binding specificity of oligosaccharides for xgalectin-VIIa was analyzed by frontal affinity chromatography (FAC). The oligosaccharide specificity pattern of xgalectin-VIIa was similar to that of the human homolog galectin-3, and it was also shown that the N-acetyllactosamine type, biantennary N-glycans exhibit high affinity for xgalectin-VIIa (Kd = 11 microM). These results suggest that xgalectin-VIIa interacts with xCGLs through binding to N-acetyllactosamine type N-glycans and that this interaction might make it possible to organize a lectin network involving members of different lectin families.
Shoji
Hiroki
H
Department of Endocrinology, Kagawa University, 1750-1 Ikenobe, Kita-gun, Kagawa 761-0793, Japan.
Ikenaka
Kazuhiro
K
Nakakita
Shin-ichi
S
Hayama
Koh
K
Hirabayashi
Jun
J
Arata
Yoichiro
Y
Kasai
Ken-ichi
K
Nishi
Nozomu
N
Nakamura
Takanori
T
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002236:Carbohydrate Conformation; D002846:Chromatography, Affinity; D017931:DNA Primers; D037161:Galectins / Q000378:metabolism*; D037102:Lectins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D020349:Surface Plasmon Resonance; D014981:Xenopus
D017931:DNA Primers; D037161:Galectins; D037102:Lectins; D011134:Polysaccharides