Protein: Polypeptide N-acetylgalactosaminyltransferase (S5S833)
Organism: Biomphalaria glabrata (Bloodfluke planorb) (Freshwater snail)
Function: Catalyzes the initial reaction in O-linked oligosaccharide biosynthesis, the transfer of an N-acetyl-D-galactosamine residue to a serine or threonine residue on the protein receptor. Has a broad substrate specificity. Acceptor peptides include Muc2, Muc5Ac, Muc1a and Muc1a', with Muc2 as the best acceptor. Acts on non-glycosylated and mono- or multi- glycosylated peptide substrates. Transfers preferably to threonine rather than serine residue. Thr-15 is the most preferred site of glycosylation in Muc2 peptide PTTTPITTTTTVTPTPTPTGTQTK having proline residues at position -1, and at positions +1 and +3, where the number represents the distance from the C-terminal and N-terminal hydroxyl amino acid, respectively. Transfer of the N-acetyl-D-galactosamine (GalNAc) is optimal with proline residues at positions -3, -1, +1 and +3, but other amino acids are tolerated, although some, such as phenylalanine, isoleucine or leucine at -1, or lysine at +3 prevent the transfer completely. Second GalNAc is transferred to Muc2 Thr-2 or Thr-13, both of which have two proline residues nearby. Up to nine sites can be glycosylated within Muc2, but eight are used simultaneously since Thr-19 and Thr-21 are not detected to be glycosylated at the same time. Glycosylation is not detected of a potential site, which is next to an already glycosylated site, but only one amino acid is needed in between two glycosylation sites. Ser-5 is the preferred glycosylation site in Muc5Ac peptide GTTPSPVPTTSTTSAP into which up to four GalNAcs can be attached. Only the threonine residues are detected as pontential glycosylation sites in Muc1a APPAHGVTSAPDTRPAPGC and Muc1a' AHGVTSAPDTR peptides. Transferase activity is restricted to UDP-GalNAc as a donor, and none of the nucleotide sugars UDP-Gal, UDP-GlcNAc, GDP-fucose, UDP-xylose, UDP- glucuronic acid or CMP-neuraminic acid are utilized as donors
Subcellular location: Golgi apparatus membrane ; Single-pass type II membrane protein
InterPro domains:
- IPR045885: N-acetylgalactosaminyltransferase (domain) [167-462]
- IPR000772: Ricin B, lectin domain (domain) [471-595]
- IPR035992: Ricin B-like lectins (homologous_superfamily) [459-594]
- IPR001173: Glycosyltransferase 2-like (domain) [167-344]
- IPR029044: Nucleotide-diphospho-sugar transferases (homologous_superfamily) [103-465]
Sequence:
MVRRKLRLLVILAGIWLVGIVVYLFKGDDQSEFEKRVIDKGPDGFYVHKEEKEHQPFQEENKAEVLHQVEDQWKKKQDAEITQSRQTFIETKKLLPPDDELGDIPWGQFDELGYISKTTLKPGQDPYARNKFNLQASDNIKSNRHVPDTRHMNCRSETWSQDLPDTSVIITFHNEARSALLRTIVSIFRKSPDHLIREIILVDDFSDDPSDGQELDKIKKVKVLRNDKRQGLIRSRVNGANMAKGKVLTFLDSHCECNEKWLEPLLDRVKQDRRNVVSPIIDVISMDNFDYIGASADLKGGFDWNLVFKWDYMSAEERNRQRQNPTAPIRTPMIAGGLFSIDKSWFDELGQYDLKMDVWGGENLEISFRVWQCHGNLEIIPCSRVGHVFRKQHPYTFPGGSGQIFARNTKRAAEVWMDEYIQFYFAAVPSAKHVDVGDISERLALRDRLQCKPFKWFLENVYPELKIPSVQDIAFGSIKQGNDCMDTMGHFADGILGLYPCHNSGGNQEFSLTKAGEVKHLDLCVTLVDTRPGNEVKLYQCTPGNYKQQFVQNPAKDQLRHKSYDLCLDSVVWQTKGIVANKCDPSSYTQKWTFSLSKNR
Predicted GO terms:
Molecular Function (MF): GO:0003674 (molecular function), GO:0003824 (catalytic activity), GO:0016740 (transferase activity), GO:0140096 (catalytic activity, acting on a protein), GO:0016757 (glycosyltransferase activity), GO:0004653 (polypeptide N-acetylgalactosaminyltransferase activity), GO:0016758 (hexosyltransferase activity), GO:0008194 (UDP-glycosyltransferase activity), GO:0008376 (acetylgalactosaminyltransferase activity)
Biological Process (BP): GO:0008150 (biological process), GO:0008152 (metabolic process), GO:0009987 (cellular process), GO:0009058 (biosynthetic process), GO:0044238 (primary metabolic process), GO:0044237 (cellular metabolic process), GO:0071704 (organic substance metabolic process), GO:0006807 (nitrogen compound metabolic process), GO:0070085 (glycosylation), GO:0044249 (cellular biosynthetic process), GO:1901564 (organonitrogen compound metabolic process), GO:1901576 (organic substance biosynthetic process), GO:0044260 (cellular macromolecule metabolic process), GO:0043170 (macromolecule metabolic process), GO:0043413 (macromolecule glycosylation), GO:1901135 (carbohydrate derivative metabolic process), GO:0019538 (protein metabolic process), GO:0036211 (protein modification process), GO:1901566 (organonitrogen compound biosynthetic process), GO:0009059 (macromolecule biosynthetic process), GO:0006486 (protein glycosylation), GO:0043412 (macromolecule modification), GO:0034645 (cellular macromolecule biosynthetic process), GO:1901137 (carbohydrate derivative biosynthetic process), GO:0009100 (glycoprotein metabolic process), GO:0009101 (glycoprotein biosynthetic process), GO:0006493 (protein O-linked glycosylation)
Cellular Component (CC): GO:0005575 (cellular component), GO:0110165 (cellular anatomical entity), GO:0005622 (intracellular anatomical structure), GO:0043226 (organelle), GO:0005737 (cytoplasm), GO:0012505 (endomembrane system), GO:0005794 (Golgi apparatus), GO:0043229 (intracellular organelle), GO:0043227 (membrane-bounded organelle), GO:0043231 (intracellular membrane-bounded organelle)