Endoplasmic reticulum-associated degradation of newly synthesized glycoproteins has been demonstrated previously using various mammalian cell lines. Depending on the cell type, glycoproteins bearingMan9 glycans and glycoproteins bearing Man5 glycans can be efficiently degraded. Awide variety of variables can lead to defective synthesis of lipid-linked oligosaccharides and, therefore, in mammalian cells, species derived fromMan9GlcNAc2 orMan5GlcNAc2 are often recovered on newly synthesized glycoproteins. .
