Tulipa gesneriana agglutinin (TxLC-I)
Tulipa gesneriana agglutinin (TxLC-I) is isolated from tulip bulbs and purified by affinity column chromatography on a Fetuin-Sepharose 4B gel. Tulipa gesneriana lectin (TxLMII), the other carbohydrate-binding protein contained in tulip bulbs is isolated during extraction and could be purified as the same manner with an additionnal affinity chromatography step on a Mannose-Sepharose 4B gel.
Contrary to TxLM-II (a mannose-specific lectin), carbohydrate domain of TxLC-I is more complex with a Gal/GalNAc binding domain. TxLC-I was originally described as a tetramer of four identical subunits of 28 kDa. Then, after amino acid sequence analyses, this subunit seems to be partialy cleaved into two smaller polypeptides of approximatively 14 kDa each.
TxLC-I shows the highest affinity to :
- triantennary carbohydrates with three Gal residues (especially, Gal with β(1-3) linkage at non-reducing termini).
- diantennary oligosaccharides with a fucose residue linked through α(1-6) linkage to the innermost GlcNAc. In this case, fucose residue increase considerably the lectin binding.
TxLC-I agglutinates mouse and rat erythrocytes. Moreover, TxLC-I showed potent mitogenic activity on mouse and human lymphocytes.
H. T. Preis