Glycosyltransferases catalyze the transfer of an activated monosaccharide, such as a nucleotide sugar, to an acceptor substrate. One of the most important elements in protein-carbohydrate recognition events is the poly-LacNAc structure. This polymer consists of the monomeric sugars Galactose (Gal) and N-Acetylglucosamine (GlcNAc) and occurs either as Poly-LacNAc type I (Galβ1-3GlcNAc) or type II (Galβ1-4GlcNAc). Our working group established a highly efficient way for the synthesis of Poly-LacNAc type II from the nucleotide sugars UDP-Gal and UDP-GlcNAc by the combination of the human β1,4-galactosyltransferase-1 (β4GalT-1) and β1-3-N-acetylglucosaminyltransferase (β3GlcNAcT) from Helicobacter pylori (PUBLICATION Rech et al. 2011). The products of this reaction can be further used for carbohydrate-lectin interaction studies (LINK galectines) and as backbones for several other bioactive polymers, e.g. the Galili-epitope (Gal(α1-3)Gal(β1-4)GlcNAc(β1-R)) or the HNK-1 epitope.