Comparison of DDM and digitonin extraction for BN-PAGE analysis of COPII vesicles. ER budding in WT SICs and analysis of γ-secretase complexes extracted by either 0.5% DDM or 1% digitonin using BN-PAGE followed by Western blotting for anti-NCT, -APH1A, and -PSEN1 fragments. In the case of DDM-extracted samples, both full complexes and subcomplexes and dimeric complexes were distinguished. Only monomeric NCT and dimeric NCT/APH1A subcomplexes exit the ER in an Sar1-dependent manner. In the case of 1% digitonin, essentially only full complexes were detected, but they lack Sar1 dependency in ER budding.