FUNCTION: Catalyzes the initial reaction in O-linked oligosaccharide biosynthesis, the transfer of an N-acetyl-D-galactosamine (GalNAc) residue from UDP-GalNAc to a serine or threonine residue on the protein receptor (PubMed:12407114, PubMed:22186971). Generates GalNAc-O-Ser/Thr structure also known...
FUNCTION: Catalyzes the initial reaction in O-linked oligosaccharide biosynthesis, the transfer of an N-acetyl-D-galactosamine (GalNAc) residue from UDP-GalNAc to a serine or threonine residue on the protein receptor (PubMed:12407114, PubMed:22186971). Generates GalNAc-O-Ser/Thr structure also known as Tn antigen, which itself is immunogenic but also serves as a precursor for the synthesis of different mucin-type O-glycan core structures (PubMed:12407114). Contributes to the synthesis of O-linked glycans on mucins and proteoglycans of the central nervous system. May promote neurogenesis through glycosylation and stabilization of PDPN (PubMed:12407114, PubMed:22186971) (By similarity). {ECO:0000250|UniProtKB:Q8CF93, ECO:0000269|PubMed:12407114, ECO:0000269|PubMed:22186971}.; FUNCTION: [Isoform 1]: Can glycosylate both unmodified peptides and glycopeptides that already contain an O-linked GalNAc sugar. Transfers GalNAc to Thr-/Ser-rich tandem repeats GTTPSPVPTTSTTSAP of MUC5AC, specifically on Thr-3 of non-glycosylated MUC5AC peptide, on Thr-12 and Thr-13 of preglycosylated MUC5AC at Thr-3 (MUC5AC-3), on Thr-3 of preglycosylated MUC5AC at Thr-13 (MUC5AC-13) and on Thr-12 of preglycosylated MUC5AC at Thr-3 and Thr-13 (MUC5AC-3,13). Transfers GalNAc to three consecutive serine/threonine residues on SDC3 forming a triplet-Tn epitope expressed in Purkinje cells of the developing brain. {ECO:0000269|PubMed:12407114, ECO:0000269|PubMed:22186971}.; FUNCTION: [Isoform 3]: Can glycosylate both unmodified peptides and glycopeptides that already contain an O-linked GalNAc sugar. Transfers GalNAc to Thr-/Ser-rich tandem repeats GTTPSPVPTTSTTSAP of MUC5AC, specifically on Thr-3 of non-glycosylated MUC5AC peptide, on Thr-12 and Thr-13 of preglycosylated MUC5AC at Thr-3 (MUC5AC-3), on Thr-3 of preglycosylated MUC5AC at Thr-13 (MUC5AC-13) and on Thr-12 of preglycosylated MUC5AC at Thr-3 and Thr-13 (MUC5AC-3,13). {ECO:0000269|PubMed:22186971}.
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GO - Biological processes (BP):
O-glycan processing [GO:0016266]; protein O-linked glycosylation via serine [GO:0018242]; protein O-linked glycosylation via threonine [GO:0018243]...
O-glycan processing [GO:0016266]; protein O-linked glycosylation via serine [GO:0018242]; protein O-linked glycosylation via threonine [GO:0018243]
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GO - Molecular function (MF):
carbohydrate binding [GO:0030246]; metal ion binding [GO:0046872]; polypeptide N-acetylgalactosaminyltransferase activity [GO:0004653]...
carbohydrate binding [GO:0030246]; metal ion binding [GO:0046872]; polypeptide N-acetylgalactosaminyltransferase activity [GO:0004653]
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GO - Cellular component (CC):
Golgi apparatus [GO:0005794]; Golgi membrane [GO:0000139]; integral component of membrane [GO:0016021]...
Golgi apparatus [GO:0005794]; Golgi membrane [GO:0000139]; integral component of membrane [GO:0016021]
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