Three-Dimensional Structures of Galectins

The galectins are a family of beta-galactoside-specific animal lectins that contain a conserved carbohydrate recognition domain (CRD) with approximately 140 amino acid residues. There are 14 members in the mammalian galectin family (galectin-1-10, and 1115), and they have different specificities for oligosaccharides. X-ray structures of the galectin CRD in complexes with oligosaccharides have provided important clues about the oligosaccharide-recognition mechanisms of galectins giving the different specificities. Galectin is divalent in glycan binding due to the association of two CRDs that crosslink with oligosaccharides. The spatial arrangement of the two CRDs is very important for elucidating the biological functions of galectins. Several different spatial arrangements of CRDs are found in X-ray structures of galectins. I herein examined the three-dimensional structures of galectins relevant for biological functions, based on the protein-ligand interactions related with oligosaccharide-specificity, the cross-linking structure by galectin and oligosaccharides, and the spatial arrangements of CRDs.