title: Xanthosoma sagittifolium tubers contain a lectin with two different types of carbohydrate-binding sites.
abstract: An unusual lectin possessing two distinctly different types of carbohydrate-combining sites was purified from tubers of Xanthosoma sagittifolium L. by consecutive passage through two affinity columns, i.e. asialofetuin-Sepharose and invertase-Sepharose. SDS-polyacrylamide gel electrophoresis, N-terminal amino acid sequencing, and gel filtration chromatography of the purified lectin showed that the X. sagittifolium lectin is a heterotetrameric protein composed of four 12-kDa subunits (alpha(2)beta(2)) linked by noncovalent bonds. The results obtained by quantitative precipitation and hapten inhibition assays revealed that the lectin has two different types of carbohydrate-combining sites: one type for oligomannoses, which preferentially binds to a cluster of nonreducing terminal alpha1,3-linked mannosyl residues, and the other type for complex N-linked carbohydrates, which best accommodates a non-sialylated, triantennary oligosaccharide with N-acetyllactosamine (i.e. Galbeta1,4GlcNAc-) or lacto-N-biose (i.e. Galbeta1,3GlcNAc-) groups at its three nonreducing termini.
authors.affiliation: Department of Biological Chemistry, University of Michigan, Medical School, Ann Arbor, Michigan 48109-0606, USA.
authors.forename: H
authors.initials: H
authors.lastname: Mo
authors.forename: K G
authors.initials: KG
authors.lastname: Rice
authors.forename: D L
authors.initials: DL
authors.lastname: Evers
authors.forename: H C
authors.initials: HC
authors.lastname: Winter
authors.forename: W J
authors.initials: WJ
authors.lastname: Peumans
authors.forename: E J
authors.initials: EJ
authors.lastname: Van Damme
authors.forename: I J
authors.initials: IJ
authors.lastname: Goldstein
mesh_terms: D002240:Carbohydrate Sequence; D037102:Lectins / Q000737:chemistry* / Q000302:isolation & purification; D008969:Molecular Sequence Data; D008970:Molecular Weight; D037121:Plant Lectins; D010944:Plants / Q000737:chemistry*; D011233:Precipitin Tests; D011487:Protein Conformation
chemical_list: D037102:Lectins; D037121:Plant Lectins