AcrB is an inner membrane-associated transporter and component of the constitutively expressed, multidrug efflux system AcrAB in E. coli.1 It forms a complex with periplasmic and oligomeric AcrA in the presence and absence of the outer membrane component TolC to directly transport substrates from the cell interior to the periplasm. AcrB is encoded by acrAB which is upregulated in multiple-antibiotic-resistant E. coli strains, and deletion of acrAB incrEAses E. coli susceptibility to various antibiotics (MICs = 1.25-100 and 0.3-5 mg/l for wild-type and DacrAB E. coli strains, respectively).2 Technical Information Synonyms Multidrug Efflux Pump Subunit AcrB Purity 95% Source C-terminally His-tagged AcrB (E. coli K12 recombinant) purified from E. coli Amino Acids Full length, wild-type sequence MW 114.6 kDa Formulation 25 mM disodium phosphate, 150 mM sodium chloride, and 0.01