Proteins with major folding defects are extracted from futile folding cycles in the calnexin chaperone system and the ER Quality Control Compartment, and are translocated back to the cytosol for ER-associated degradation (ERAD). The N-glycan is used as a signal to distinguish proteins to be degraded, by direct binding to a ubiquitin ligase complex composed of, minimally, an E3 ubiquitin-protein ligase, protein sel-1 homolog 1 (SEL1L), derlin-2 (DERL2) and protein OS-9 (OS9) (Christianson et al. 2008, Bernasconi et al. 2008, Alcock & Swanton 2009; review Olzmann et al. 2013).