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.