Structural analysis of the recognition mechanism of poly-N-acetyllactosamine by the human galectin-9 N-terminal carbohydrate recognition domain

Glycobiology. 2009 Feb;19(2):112-7. doi: 10.1093/glycob/cwn121. Epub 2008 Oct 31.


Galectins are a family of beta-galactoside-specific lectins bearing a conserved carbohydrate recognition domain. Interactions between galectins and poly-N-acetyllactosamine sequences are critical in a variety of biological processes. Galectin-9, a member of the galectin family, has two carbohydrate recognition domains at both the N- and C-terminal regions. Here we report the crystal structure of the human galectin-9 N-terminal carbohydrate recognition domain in complex with N-acetyllactosamine dimers and trimers. These complex structures revealed that the galectin-9 N-terminal carbohydrate recognition domain can recognize internal N-acetyllactosamine units within poly-N-acetyllactosamine chains. Based on these complex structures, we propose two putative recognition modes for poly-N-acetyllactosamine binding by galectins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Crystallography, X-Ray
  • Galectins / chemistry*
  • Galectins / metabolism*
  • Humans
  • Models, Molecular
  • Polysaccharides / chemistry*
  • Polysaccharides / metabolism*
  • Protein Conformation
  • Protein Structure, Tertiary


  • Galectins
  • LGALS9 protein, human
  • Polysaccharides
  • poly-N-acetyllactosamine