title: X-ray crystal structure of the human dimeric S-Lac lectin, L-14-II, in complex with lactose at 2.9-A resolution.
abstract: S-Lac lectins are a family of soluble lactose-binding animal lectins, some of which have been implicated in modulating cell-cell and cell-matrix interactions through specific carbohydrate-mediated recognition. We report here the x-ray crystal structure of a representative member of this family, the human dimeric S-Lac lectin, L-14-II, in complex with lactose, at 2.9-A resolution. The two-fold symmetric dimer is made up of two extended anti-parallel beta-sheets, which associate in a beta-sandwich motif. Remarkably, the L-14-II monomer shares not only the same topology, but a very similar beta-sheet structure with that of the leguminous plant lectins, suggesting a conserved structure-function relationship. Carbohydrate binding by L-14-II was found to involve protein residues that are very highly conserved among all S-Lac lectins. These residues map to a single DNA exon, suggesting a carbohydrate binding cassette common to all S-Lac lectins.
authors.affiliation: Department of Molecular and Medical Genetics, University of Toronto, Ontario, Canada.
authors.forename: Y D
authors.initials: YD
authors.lastname: Lobsanov
authors.forename: M A
authors.initials: MA
authors.lastname: Gitt
authors.forename: H
authors.initials: H
authors.lastname: Leffler
authors.forename: S H
authors.initials: SH
authors.lastname: Barondes
authors.forename: J M
authors.initials: JM
authors.lastname: Rini
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D050260:Carbohydrate Metabolism; D018360:Crystallography, X-Ray; D037161:Galectins; D006388:Hemagglutinins / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D006860:Hydrogen Bonding; D007785:Lactose / Q000737:chemistry*; D037102:Lectins / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
chemical_list: D037161:Galectins; D006388:Hemagglutinins; D037102:Lectins; D007785:Lactose