Oligosaccharyltransferase complex subunits
oligosaccharyltransferase complex subunits
Oligosaccharyltransferase or OST ( EC 2.4.1.119 ) is a membrane protein complex that transfers a 14- sugar oligosaccharide from dolichol to nascent protein. It is a type of glycosyltransferase. The sugar Glc 3Man 9GlcNAc 2 (where Glc= Glucose, Man= Mannose, and GlcNAc= N-acetylglucosamine ) is attached to an asparagine (Asn) residue in the sequence Asn-X- Ser or Asn-X- Thr where X is any amino acid except proline. This sequence is called a glycosylation sequon. The reaction catalyzed by OST is the central step in the N -linked glycosylation pathway.