E3 ubiquitin-protein ligase that regulates cell proliferation. Involved in apoptosis regulation. Mediates ER stress-induced activation of JNK signaling pathway and apoptosis by promoting ERN1 activation and splicing of XBP1 mRNA. Also involved in protein trafficking and localization.
Subcellular locations: Endoplasmic reticulum membrane, Late endosome membrane, Lysosome membrane, Nucleus inner membrane
Under certain conditions, relocalizes to recycling endosomes and to the inner nuclear membrane.