Glycosylation using GalNac-T4 transferase

The invention concerns protein glycosylation, and in particular, the glycosylation of protein or polypeptide substrates using human or animal GalNAc-T4 transferase. In another aspect, the invention concerns the generation and high-level secreted expression of glycosyltransferase enzymes, and other transmembrane proteins, in mammalian host cells. The use of human polypeptide N-acetylgalactosaminytransferase T-4 (GalNAc-T4) to glycosylate substrates is disclosed. The action of GalNAc-T4 can complement the activities of GalNAc-T1, -T2 and -T3. The glycosylated substrates are useful in preparation of vaccines and anti-inflammatory agents. A method of producing the soluble form of the enzyme is also disclosed.