Recombinant expression of a galectin from the sheep gastrointestinal parasite Teladorsagia circumcincta: its use in isolating galectin-glycoconjugates.

Galectins, or beta-galactoside-binding lectins, are a family of proteins that have been described in vertebrates and, more recently, invertebrates, including nematode parasites. A tandem repeat-type galectin from the sheep gastrointestinal parasite, Teladorsagia circumcincta, has previously been isolated and the cDNA cloned. This molecule and each of its domains were expressed as fusion proteins with glutathione S-transferase (GST). The full-length molecule and the C-terminal domain were expressed in soluble form and the purified fusion proteins demonstrated a capacity to bind beta-galactoside sugars, with the greatest preference for lactose. The full-length fusion protein was used to successfully isolate potential galectin-glycoconjugates from within the parasite and from sheep serum.