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Figure S2. SEL1L interacts with RI₃₃₂ 293T cells transfected with RI₃₃₂ that were pulse-labeled for 5 h in the presence of 50 µM of proteasome inhibitor ZL₃VS. The digitonin lysates were split in two and immunoprecipitated with SEL1L antibodies and normal rabbit serum (NRS), respectively. Both immunoprecipitates were analyzed for RI and SEL1L in reimmunoprecipitation experiments (c). b shows the same immunoprecipitates for untransfected cells as a control. A fraction of the transfected cells were lysed in SDS and analyzed for levels of RI₃₃₂ and endogenous RI with cells that had not been exposed to proteasome inhibitor, as a control for the deglycosylated intermediate of RI₃₃₂ (a). d is an overexposure of the SEL1L immunoprecipitates from c. A 10% SDS polyacrylamide gel is shown.