Lipid-linked high-mannose oligosaccharide

As discussed in Chapter 6, transmembrane proteins usually have a number of posttranslational modifications that provide additional chemical groups to fulfill requirements of the three-dimensional structure. The amino terminus (residues 1-34) extends out of the membrane and has branched high mannose oligosaccharides linked through N -glycosidic bonds to the amide of asparagine (see Fig. 7.10). It is anchored in the lipid plasma membrane by a palmitoyl group that forms a thioester with the SH residue of a cysteine. The COOH terminus, which extends... 

The biosynthesis of the N-linked oligosaccharide chain is initiated by the assembly of the high mannose type of oligosaccharide on the ER membrane (Figure 2). This assembly process involves the participation of a carrier molecule called dolichyl-phosphate (Dol-P), which is a component of the ER membrane, and is a lipid structure... 

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