A novel human UDP-N-acetyl-D-galactosamine : polypeptide N-acetylgalactosaminyltransferase, GalNAc-T7, with specificity for partial GalNAc-glycosylated acceptor substrates

A novel member of the human UDP-N-acetyl-D-galactosamine:polypeptide N-acet ylgalactosaminyltransferase gene family, designated GalNAc-T7, was cloned a nd expressed. GalNAc-T7 exhibited different properties compared to other ch aracterized members of this gene family, in showing apparent exclusive spec ificity for partially GalNAc-glycosylated acceptor substrates. GalNAc-T7 sh elved no activity with a large panel of non-glycosylated peptides, but was selectively activated by partial GalNAc glycosylation of peptide substrates derived from the tandem repeats of human MUC2 and rat submaxillary gland m ucin, The function of GalNAc-T7 is suggested to be as a follow-up enzyme in the initiation step of O-glycosylation. (C) 1999 Federation of European Bi ochemical Societies.