Phage display cDNA cloning of protein with carbohydrate affinity

Cell surface complex carbohydrate structures that are synthesized through the actions of glycosyltransferases play an important role in cell-to-cell and cell-to-extracellular matrix interactions. To examine the feasibility of phage display technique to clone cDNAs encoding glycosyltransferases, we performed biopanning experiments using human histo-blood group A transferase as a model enzyme and its substrate, blood group H-specific glycoproteins, as a bait ligand. Our attempts have been unsuccessful, possibly because of the enzyme's weak affinity with the target. However, we have selectively enriched several phage clones that expressed capsid proteins fused with galectin-3, a galactose/lactose-specific animal lectin of the galectin family. These results demonstrate that this novel approach of phage display is useful in cDNA cloning of proteins with carbohydrate-binding property.