What is the substrate for oligosaccharide transferase?

What is the substrate for oligosaccharide transferase?

During the translocation of proteins in the ER, an enzyme complex called oligosaccharyltransferase (OST) transfers an oligosaccharide (OS) moiety from the dolichol-linked donor substrate to asparagine residues located within the consensus sequence -Asn-Xaa-Ser/Thr- (where Xaa is any amino acid except Pro) to form N- …

What kind of protein is Oligosaccharyltransferase?

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.

Where are oligosaccharyltransferase found?

In the central reaction of the pathway, oligosaccharyltransferase (OST), a multimeric complex located at the membrane of the endoplasmic reticulum, transfers a preassembled oligosaccharide to selected asparagine residues within the consensus sequence asparagine-X-serine/threonine.

What is the function of Dolichol?

Dolichol (long-chain polyprenols containing an α-saturated isoprene unit) acts as glycosyl carrier lipids in the biosynthesis of N-linked glycoproteins. Since alcohol dehydrogenase (ADH) oxidizes this compound, an influence of alcohol intake on catabolism of dolichols has been suggested.

What are examples of oligosaccharides?

Oligosaccharides are formed when two or more monosaccharides join together by O-glycosidic bonds. Examples include sucrose, lactose and maltose. Specific enzymes are used to catalyze the glycosidic bonds in olgosaccharides and each sugar must be specific to each enzyme used for each new glycosidic bond.

What is oligosaccharide formula?

Common oligosaccharides It is a trisaccharide formed from the combination of three monomers: galactose, glucose, and fructose. It has a chemical formula of C18H32O16.

Where is the active site of oligosaccharide transferase?

Location. A lipid-linked core-oligosaccharide is assembled at the membrane of the endoplasmic reticulum and transferred to selected asparagine residues of nascent polypeptide chains by the oligosaccharyl transferase complex. The active site of OST is located about 4 nm from the lumenal face of the ER membrane.

How is oligosaccharide transfered from dolichol to Ost?

Oligosaccharyltransferase or OST (EC 2.4.1.119) is a membrane protein complex that transfers a 14-sugar oligosaccharide from dolichol to nascent protein.

Which is a type of glycosyltransferase or Ost?

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.

Which is the catalytically active subunit of oligosaccharide?

Activate the Asn amide nitrogen atom for the actual transfer of oligosaccharide. Release its substrates. The catalytically active subunit of the OST is called STT3. Two paralogs exist in eukaryotes, termed STT3A and STT3B.