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

摘要

>A novel member of the human UDP-N-acetyl- class="smallCaps">D-galactosamine:polypeptide N-acetylgalactosaminyltransferase gene family, designated GalNAc-T7, was cloned and expressed. GalNAc-T7 exhibited different properties compared to other characterized members of this gene family, in showing apparent exclusive specificity for partially GalNAc-glycosylated acceptor substrates. GalNAc-T7 showed 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 mucin. The function of GalNAc-T7 is suggested to be as a follow-up enzyme in the initiation step of O-glycosylation.