BAT3 could still be involved in the dislocation reaction when in close proximity to the ER membrane, because at least some of the dislocation intermediate observed upon expression of the EBVDUB remains loosely associated with the ER membrane. We therefore examined whether BAT3 engages any of the known dislocation components that localize to the ER membrane. We readily retrieved BAT3 in association with Derlin2, a small membrane protein implicated in ER quality control . Although BAT3 is Cefdinir reported to localize to the nucleus, we demonstrated additional co-localization with Derlin2 by immunofluorescence microscopy, in line with assigned roles for BAT3 in the cytosol. In order to characterize this interaction further, we examined the consequences of overexpression of Derlin2. The stoichiometry of multi-protein complexes can be disturbed by overexpression of one of its components. We recovered a reduced amount of BAT3 upon overexpression of Derlin2, and we observed an even more obvious reduction when we overexpressed a Derlin2-GFP fusion protein. The latter effect we ascribe to the bulk of the appended GFP moiety, which would sterically hinder these interactions. We conclude that BAT3 can interact with a dislocation substrate and that it is recruited to the site of dislocation through interactions with Derlin2, although our data do not distinguish between direct and indirect interactions. Of note, members of the Derlin family have been speculated to form a channel that facilitates passage of misfolded polypeptides from the lumen of the ER across the ER membrane to the cytoplasm. Having shown interactions between BAT3 and Ri332, and between BAT3 and Derlin2, we set out to Lucidenic-acid-C visualize these complexes by microscopy. As Ri332 is rapidly destroyed, we reasoned that we could best visualize any such complex by inhibiting degradation. To this end, we interfered with degradation by expression of a dominant negative version of YOD1 or the EBV protease domain targeted to p97 . Hela cells were transiently transfected with Ri332, upon which the various types of blockade were imposed. After fixation, cells were permeabilized and triple-labeled for Ri332, Derlin2 and BAT3. We directed our attention to cells with a strong signal for the dislocation substrate, as an indication of successful inhibition of degradation. In control cells, we observed clear co-localization of Ri332, BAT3 and Derlin2 consistent with the notion that BAT3 can engage a misfolded ER luminal glycoprotein at the site of dislocation.