InterPro domain: IPR036330

Ost4 is a very short, approximately 30 residues, enzyme found from fungi to vertebrates. It is a member of the ER oligosaccaryltansferase complex, 2.4.1.119 , that catalyses the asparagine-linked glycosylation of proteins. It appears to be an integral membrane protein that mediates the en bloc transfer of a pre-assembled high-mannose oligosaccharide onto asparagine residues of nascent polypeptides as they enter the lumen of the rough endoplasmic reticulum.