polypeptide N-acetylgalactosaminyltransferase 10 (protein-UDP acetylgalactosaminyltransferase 10, UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase 10, polypeptide GalNAc transferase 10, GalNAc-T10, pp-GaNTase 10, GALNT10)

Function

• glycosylation pathway
• catalyzes the initial reaction in O-linked oligosaccharide biosynthesis, transfer of an N-acetyl-D-galactosamine residue to Ser or Thr on the nascent glycoprotein
• activity toward Muc5Ac & EA2 peptide substrates
• in rat, this enzyme may be unable to transfer GalNAc onto Ser or Thr on the nascent protein, but instead requires prior addition of a GalNAc before adding additional GalNAc moieties

UDP-N-acetyl-D-galactosamine + polypeptide  <-->
           UDP + N-acetyl-D-galactosaminyl-polypeptide

Cofactor: Mn+2, Ca+2

Structure

• 2 conserved domains in the glycosyltransferase region:
  • N-terminal domain (domain A, GT1 motif), role in Mn+2 coordination & substrate binding
  • C-terminal domain (domain B, Gal/GalNAc-T motif), role in catalytic reaction & UDP-Gal binding
• belongs to the glycosyltransferase 2 family, GalNAc-T subfamily.
• contains 1 ricin B-type lectin domain ricin B-type lectin domain binds to GalNAc & contributes to glycopeptide specificity

Compartment

Golgi apparatus membrane

Alternative splicing

named isoforms=4

Expression

• widely expressed
• expressed in small intestine > stomach, pancreas, ovary, thyroid, spleen > other tissues

More general terms

• glycosyltransferase

Database

• OMIM: https://mirror.omim.org/entry/608043
• UniProt: http://www.uniprot.org/uniprot/Q86SR1.html