1AFB

STRUCTURAL BASIS OF GALACTOSE RECOGNITION IN C-TYPE ANIMAL LECTINS

Summary for 1AFB

• Entry DOI: 10.2210/pdb1afb/pdb
• Descriptor: MANNOSE-BINDING PROTEIN-A, 2-acetamido-2-deoxy-beta-D-galactopyranose, CALCIUM ION, ... (5 entities in total)
• Functional Keywords: c-type lectin, calcium-binding protein, lectin
• Biological source: Rattus norvegicus (Norway rat)
• Total number of polymer chains: 3
• Total formula weight: 52171.12

Authors

Kolatkar, A.R.,Weis, W.I. (deposition date: 1995-11-03, release date: 1996-04-03, Last modification date: 2024-11-20)

Primary citation

Kolatkar, A.R.,Weis, W.I.
Structural basis of galactose recognition by C-type animal lectins.
J.Biol.Chem., 271:6679-6685, 1996

PubMed Abstract: 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.

PubMed: 8636086
DOI: 10.1074/jbc.271.12.6679

Experimental method

X-RAY DIFFRACTION (1.9 Å)