This entry represents the Der1-like family, which includes yeast Der1 and its mammalian homologues, the Derlins. Der1 is a component of the Hrd1 ubiquitin ligase complex required for ER-associated degradation (ERAD) of misfolded luminal glycoproteins ...
This entry represents the Der1-like family, which includes yeast Der1 and its mammalian homologues, the Derlins. Der1 is a component of the Hrd1 ubiquitin ligase complex required for ER-associated degradation (ERAD) of misfolded luminal glycoproteins [1]. The cryo-EM structure reveals that Der1 contains six transmembrane segments and is structurally similar to rhomboid proteases, though it lacks catalytic activity [2]. Der1 has a lateral gate between transmembrane helices 2 and 5, and a hydrophilic luminal cavity. Unlike rhomboids, the luminal cavity of Der1 is perpetually open due to a shorter loop between TM5 and TM6 [2]. Within the Hrd1 complex, Der1 is linked to Hrd1 via the Usa1 protein on the cytosolic side. The lateral gates of Der1 and Hrd1 face one another and together form a retrotranslocon, with Der1 providing the luminal half-channel and Hrd1 providing the cytosolic half-channel [2]. The region between the lateral gates corresponds to a thinned membrane, facilitated in part by hydrophilic residues in TM2 of Der1. Der1 is required for stable loop insertion of substrates during retrotranslocation across the ER membrane [2].