Incorporation of N-acetyl glucosamine into lipid linked oligosaccharides

When beef liver microsomes are labeled with UDP-[3H]N-acetyl glucosamine, three different lipid-bound saccharides are labeled: dolichol pyrophosphoryl-GlcNAc, dolichol pyrophosphoryl-(GlcNAc)2 and a previously uncharacterized compound (component III). Incubation with UDP leads to the disappearance of dolichol pyrophosphoryl-(GlcNac)2 from microsomes prelabeled with UDP-3H-N-acetyl glucosamine. This result provides further support for the suggestion of Leloir et al. (6) that dolichol pyrophosphoryl-(GlcNAc)2 is synthesized from dolichol pyrophosphoryl-GlcNAc and UDP-N-acetyl glucosamine. Component III cannot be discharged with UMP or UDP. It elutes from DEAE-cellulose exactly as the other components. The saccharide portion of component III has a molecular weight of 800–900 and contains glucose in addition to N-acetyl glucosamine.