Non-denaturing native-PAGE was performed as described 6 (link). Briefly, Tris-glycine polyacrylamide gels (4.5% stacking gel and a 7.5% separation gel) were used to separate purified proteins or proteins from mammalian cell lysates to detect BiP oligomers. The separation was performed in running buffer (25 mM Tris, 192 mM glycine, pH ~8.8) at 120 V for 2 hours. Afterwards, the proteins were visualized by staining with InstantBlue Coomassie solution (expedeon) or transferred to a polyvinylidene difluoride (PVDF) membrane in blotting buffer (48 mM Tris, 39 mM glycine; pH ~9.2) supplemented with 0.04 (w/v) SDS for 16 hours at 30 V for immunodetection. The membrane was washed for 20 minutes in blotting buffer (without SDS) supplemented with 20% (v/v) methanol before blocking. Seven µg of purified BiP protein was loaded per lane to detect purified BiP proteins by Coomassie staining and volumes of lysates corresponding to 30 µg of total protein were loaded per lane to detect endogenous BiP from CHO-K1 cell lysates by immunoblotting.