Magnesium transporter protein 1 (Magt1)

Acts as accessory component of the N-oligosaccharyl transferase (OST) complex which catalyzes the transfer of a high mannose oligosaccharide from a lipid-linked oligosaccharide donor to an asparagine residue within an Asn-X-Ser/Thr consensus motif in nascent polypeptide chains. Involved in N-glycosylation of STT3B-dependent substrates.

Specifically required for the glycosylation of a subset of acceptor sites that are near cysteine residues; in this function appears to act redundantly with TUSC3. In its oxidized form suggested to form transient mixed disulfides with a glycoprotein substrate to ease access to STT3B into the unmodified acceptor website.