4R9A: Crystal Structure Of Human Galectin-3 Crd In Complex With Lactose (ph 7.0, Peg4000)

Galectin-3 (Gal-3) which shows affinity of beta-galactosides is a cancer-related protein. Thus, it is important to understand its ligand binding mechanism and then design its specific inhibitor. It was suggested that the positions of water molecules in Gal-3 ligand-binding site could be replaced by appropriate chemical groups of ideal inhibitors. However, the reported structures of Gal-3 carbohydrate recognition domain (CRD) complexed with lactose showed that the number of water molecules are different and the water positions are inconsistent in the ligand-binding site. This study reported four high-resolution (1.24-1.19 A) structures of Gal-3 CRD complexed with lactose, and accurately located 12 conserved water molecules in the water network of Gal-3 CRD ligand-binding site by merging these structures. These water molecules either directly stabilize the binding of Gal-3 CRD and lactose, or hold the former water molecules at the right place. In particular, water molecule 4 (W4) which only coordinates with water molecule 5 (W5) and water molecule 6 (W6) plays a key role in stabilizing galactose residue. In addition, by three-dimensional alignment of the positions of all residues, 14 flexible parts of Gal-3 CRD were found to dynamically fluctuate in the crystalline environment.
PDB ID: 4R9ADownload
MMDB ID: 127659
PDB Deposition Date: 2014/9/4
Updated in MMDB: 2015/03
Experimental Method:
x-ray diffraction
Resolution: 1.2  Å
Source Organism:
Similar Structures:
Biological Unit for 4R9A: monomeric; determined by author and by software (PISA)
Molecular Components in 4R9A
Label Count Molecule
Protein (1 molecule)
Galectin-3(Gene symbol: LGALS3)
Molecule annotation
Chemical (1 molecule)
* Click molecule labels to explore molecular sequence information.

Citing MMDB