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 misfolded glycoproteins (PubMed:16186509, PubMed:16449189). May also 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 (PubMed:26565908). (Microbial infection) In contrast to DERL1, it is not involved in the degradation of MHC class I heavy chains following infection by cytomegaloviruses. Forms homo- and heterooligomers with DERL3 and, to a lesser extent, with DERL1 (PubMed:16186509). Interacts with the SEL1L/SYVN1 and VCP/SELENOS protein complexes (PubMed:16186509). Mediates association between VCP and EDEM1, as well as that between VCP and the misfolded glycoproteins (PubMed:16449189). Interacts with OS9 (PubMed:19084021). Interacts with SELENOK and SELENOS (PubMed:22016385). Interacts with the signal recognition particle/SRP and the SRP receptor; in the process of endoplasmic reticulum stress-induced pre-emptive quality control (PubMed:26565908). Interacts with CCDC47 (By similarity). Ubiquitous. Overexpressed in various hepatocarcinomas. Up-regulated in response to endoplasmic reticulum stress via the ERN1-XBP1 pathway of the unfolded protein response (UPR). Belongs to the derlin family.