Recombinant Drosophila melanogaster Polypeptide N-acetylgalactosaminyltransferase 3 (pgant3), partial

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. It can both act as a peptide transferase that transfers GalNAc onto unmodified peptide substrates, and as a glycopeptide transferase that requires the prior addition of a GalNAc on a peptide before adding additional GalNAc moieties. Prefers EA2 as substrate. Has weak activity toward Muc5AC-3, -13 and -3/13 substrates. Plays a critical role in the regulation of integrin-mediated cell adhesion during wing development by influencing, via glycosylation, the secretion and localization of the integrin ligand Tig to the basal cell layer interface. Might have a role in protein O-glycosylation in the Golgi and thereby in establishing and/or maintaining a proper secretory apparatus structure. Together with Pgant35A, regulates integrin levels and activity-dependent integrin signaling at the synapse in neurons and muscles.