May be involved in the degradation process of specific misfolded endoplasmic reticulum (ER) luminal proteins. May also involved in endoplasmic reticulum stress-induced pre-emptive quality control, a mechanism that selectively attenuates the translocation of newly synthesized proteins into the endoplasmic reticulum and reroutes them to the cytosol for proteasomal degradation. By endoplasmic reticulum stress. Belongs to the derlin family.