The amino group at C-2 bears a fatty acid in amide linkage.

The fatty acid is usually saturated or monounsaturated, with 16, 18, 22, or 24 carbon atoms.

Ceramide is the parent compound for this group.

TLS Online TPP Program

#Id: 7947

#Unit 2. Cellular Organization

N-linked oligosaccharides

carbohydrate chains attached to the amide nitrogen of asparagine

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#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.

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#Id: 7949

#Unit 2. Cellular Organization

A branched oligosaccharide containing

3 glucose (Glc)

9 mannose (Man)

2 N-acetylglucosamine (GlcNAc)

Glc3Man9(GlcNAc)2

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#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

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#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

TLS Online TPP Program

#Id: 7952

#Unit 2. Cellular Organization

Two N- acetylglucosamine (GlcNAc) and five mannose residues are added one at a time to a dolichol phosphate on the cytosolic face of the ER membrane