YOD1 (OTU1) is a highly conserved deubiquitinating enzyme of the ovarian tumor (otubain) family. It forms a complex with Valosin containing protein (VCP, p97) that may participate in endoplasmic reticulum-associated degradation (ERAD) for misfolded lumenal proteins (Ernst et al. 2009, Kim et al. 2014). It may act by triming the ubiquitin chain on the associated substrate to facilitate their threading through the VCP/p97 pore. Ubiquitin moieties on substrates may present a steric impediment to the threading process when the substrate is transferred to the VCP pore and threaded through VCP's axial channel.