Ost4 is a very short, approximately 30 residues, enzyme found from fungi to vertebrates. It is a member of the ER oligosaccaryltansferase complex, , 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.
This entry represents OST4 from plants, including OST4A/4B/4C from Arabidopsis. They share the protein sequence similarity with animals OST4, which is part of the oligosaccharyl transferase (OST) complex that catalyses the initial transfer of a defined glycan (Glc3Man9GlcNAc2 in eukaryotes) from the lipid carrier dolichol-pyrophosphate to an asparagine residue within an Asn-X-Ser/Thr consensus motif in nascent polypeptide chains, the first step in protein N-glycosylation [].
Ost4 is a very short, approximately 30 residues, enzyme found from fungi to vertebrates. It is a member of the ER oligosaccaryltansferase complex, , 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.
