Assays for polarity of the aerR::Kanr insertion mutations. (A) Strains ES7 and ES8 contain the same Kanr gene insertion in two different orientations. (B) Spectral analysis of membrane fractions from the wild-type strain SB1003, the two aerR-disrupted mutants ES7 and ES8, and the crtJ-disrupted strain CD2-4, grown under anaerobic conditions. (C) Immunoblot analysis of the amounts of FLAG CrtJ synthesized in strains SB1003-FLAG, ES8-FLAG, and ES7-FLAG.