TLS Online TPP Program

#Id: 7946

#Unit 2. Cellular Organization

O-linked oligosaccharides

Carbohydrate chains in glycoproteins attached to the

hydroxyl group (-OH) in serine and threonine residues

TLS Online TPP Program

#Id: 7947

#Unit 2. Cellular Organization

N-linked oligosaccharides

carbohydrate chains attached to the amide nitrogen of asparagine

TLS Online TPP Program

#Id: 7948

#Unit 2. Cellular Organization

Biosynthesis of all N-linked oligosaccharides begins in the rough ER with a preformed oligosaccharide precursor containing 14 residues.

TLS Online TPP Program

#Id: 7949

#Unit 2. Cellular Organization

A branched oligosaccharide containing

3 glucose (Glc)

9 mannose (Man)

2 N-acetylglucosamine (GlcNAc)

Glc3Man9(GlcNAc)2

TLS Online TPP Program

#Id: 7950

#Unit 2. Cellular Organization

Prior to transfer to a nascent chain in the lumen of the  ER, the oligosaccharide precursor is assembled on amembrane- attached anchor called dolichol phosphate, a longchain polyisoprenoid lipid

TLS Online TPP Program

#Id: 7951

#Unit 2. Cellular Organization

First sugar residue is attached to dolichol by a high-energy pyrophosphate linkage & the other sugars are added by glycosidic bonds