Glycans in Glycoprotein Quality Control

N-Glycans affect glycoprotein folding because of their hydrophilic nature. In the endoplasmic reticulum (ER), the processing of N-glycans yields a series of truncated N-glycans that serve as checkpoints that dictate the life or death of many newly made membrane and secreted proteins. Other glycan modifications also may affect glycoprotein folding in the ER. This chapter describes glycan-mediated quality-control processes in the ER and Golgi apparatus and what happens to glycoproteins that fail their “final folding examination.”