Functional component of endoplasmic reticulum-associated degradation (ERAD) for misfolded lumenal glycoproteins, but not that of misfolded nonglycoproteins. May act by forming a channel that allows the retrotranslocation of misfolded glycoproteins into the cytosol where they are ubiquitinated and degraded by the proteasome. May mediate the interaction between VCP and the misfolded glycoproteins. May be 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. Forms homo- and heterooligomers with DERL2 and, to a lesser extent, with DERL1. Interacts with VCP and EDEM1. Interacts with SELENOK and SELENOS. Interacts with the signal recognition particle/SRP and the SRP receptor; in the process of endoplasmic reticulum stress-induced pre-emptive quality control. Belongs to the derlin family.