Characterization of a novel human UDP-GalNAc transferase, pp-GalNAc-T15.

We have cloned, expressed and characterized a novel member of the human UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase (pp-GalNAc-T) family, pp-GalNAc-T15. The pp-GalNAc-T15 transcript was ubiquitously expressed in human tissues. Recombinant pp-GalNAc-T15 transferred N-acetylgalactosamine (GalNAc) toward a panel of mucin-derived peptide substrates in vitro. Although pp-GalNAc-T15 showed significantly less catalytic activity than pp-GalNAc-T2, T15 transferred up to seven GalNAcs to the Muc5AC peptide, while T2 transferred up to five GalNAcs. These results clearly indicated that pp-GalNAc-T15 is a novel member of the human pp-GalNAc-T family with unique catalytic activity.