Anti myc clone 4a6

NuPAGE precast gradient 4–12% polyacrylamide (Thermo Fisher Scientific) was used for anti-BirA blot. All other blots are either 10% or 12.5% polyacrylamide:bis (37.5:1) gels. The membranes were incubated in 5% milk in PBS with Tween or Nonidet P-40 at 0.2%. Anti-RHBDL4 (Sigma, HPA013972) was used at 1:200. Anti-K63 linkage–specific (Abcam, EPR8590-448), anti-p97 (Thermo Scientific Pierce), anti-mCherry (GeneTex, GTX128508), and anti-myc clone 4A6 (Merck Millipore, 05-724) antibodies were all used at 1:1000. Anti–FLAG-HRP (Sigma–Aldrich A8592) was used at 1:2000 whenever indicated. Neutravidin blots were done after blocking 3% BSA in PBS, with 0.2% Tween 20; neutravidin–HRP conjugate (Thermo Fisher Scientific) was used at 1:4000 in 3% BSA in PBS. 0.1% Ponceau S stain in 1% acetic acid was used to stain nitrocellulose membranes.

The following primary rabbit polyclonal antibodies were used: anti‐PDIR, anti‐ERp57, anti‐P5, and anti‐GRP170 (all from ThermoFisher, cat. # PA3‐007, PA3‐009, PA3‐008, and PA5‐27655, respectively). In addition, a rabbit polyclonal antibody to the HA‐tag (Sigma, cat. #H6908) and a goat polyclonal antibody to reticulocalbin (Santa Cruz, cat. #sc‐109422) were used. Mouse monoclonal antibodies used were anti‐ATF6 (Abcam, cat. #ab122897), anti‐GAPDH (ThermoFisher, cat. #AM4300), anti‐V5 (Invitrogen, cat. #R960‐25), anti‐myc clone 4A6 (Merck, cat. #05‐724), anti‐HA (Sigma, cat. #H3663), and anti‐BiP (BD Biosciences, cat. #610979). A rabbit monoclonal anti‐HDAC2 was also used (Abcam, cat. #32117). The following secondary antibodies were used for Western blotting: goat anti‐mouse IRDye 800 (cat. #10751195), goat anti‐mouse IRDye 680 (cat. #A32729), goat anti‐rabbit IRDye 800 (cat. #13477187), and goat anti‐rabbit IRDye 680 (cat. #35568, all from ThermoFisher). Secondary antibodies for immunofluorescence were sheep anti‐rabbit‐FITC (Sigma, cat. #F7512) and donkey anti‐mouse‐Texas Red (Abcam, cat. #ab6818).