Xanthosoma sagittifolium tubers contain a lectin with two different types of carbohydrate-binding sites.
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.
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Department of Biological Chemistry, University of Michigan, Medical School, Ann Arbor, Michigan 48109-0606, USA.
Rice
K G
KG
Evers
D L
DL
Winter
H C
HC
Peumans
W J
WJ
Van Damme
E J
EJ
Goldstein
I J
IJ
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
D037102:Lectins; D037121:Plant Lectins