Structural basis of galactose recognition by C-type animal lectins.Kolatkar, A.R., Weis, W.I.
(1996) J.Biol.Chem. 271: 6679-6685
- PubMed: 8636086
- Primary Citation of Related Structures:  1AFA, 1AFD
- PubMed Abstract:
- Binding of Sugar Ligands to Ca+2-Dependent Animal Lectins II. Generation of High-Affinity Galactose Binding by Site-Directed Mutagenesis
Iobst, S.T.,Drickamer, K.
(1994) J.Biol.Chem. 269: 15512
- Trimeric Structure of a C-Type Mannose-Binding Protein
Weis, W.I.,Drickamer, K.
(1994) Structure 2: 1227
The asialoglycoprotein receptors and many other C-type (Ca2+-dependent) animal lectins specifically recognize galactose- or N-acetylgalactosamine-terminated oligosaccharides. Analogous binding specificity can be engineered into the homologous rat man ...
The asialoglycoprotein receptors and many other C-type (Ca2+-dependent) animal lectins specifically recognize galactose- or N-acetylgalactosamine-terminated oligosaccharides. Analogous binding specificity can be engineered into the homologous rat mannose-binding protein A by changing three amino acids and inserting a glycine-rich loop (Iobst, S. T., and Drickamer, K. (1994) J. Biol. Chem. 269, 15512-15519). Crystal structures of this mutant complexed with beta-methyl galactoside and N-acetylgalactosamine (GalNAc) reveal that as with wild-type mannose-binding proteins, the 3- and 4-OH groups of the sugar directly coordinate Ca2+ and form hydrogen bonds with amino acids that also serve as Ca2+ ligands. The different stereochemistry of the 3- and 4-OH groups in mannose and galactose, combined with a fixed Ca2+ coordination geometry, leads to different pyranose ring locations in the two cases. The glycine-rich loop provides selectivity against mannose by holding a critical tryptophan in a position optimal for packing with the apolar face of galactose but incompatible with mannose binding. The 2-acetamido substituent of GalNAc is in the vicinity of amino acid positions identified by site-directed mutagenesis (Iobst, S. T., and Drickamer, K. (1996) J. Biol. Chem. 271, 6686-6693) as being important for the formation of a GalNAc-selective binding site.
Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305, USA.