What happens to an ER protein that fails quality control? e.g., an MHC Class I HC that has failed to find β2m

1. If the MHC Class I HC has a long residence time with ER chaperones 2. this allows access of a mannosidase that removes one particular mannose 3. removing this protein from the folding environment. 4. The protein is unfolded and fed through a multisubunit DISLOCON 5. and is ubiquitylated during dislocation, which targets it to the proteasome 6. where it is deubiquitylated and degraded.