OprM, the outer membrane component of the MexAB-OprM multidrug efflux pump ofPseudomonas aeruginosa, hasbeenassumed to facilitate the export of antibiotics across the outer membrane of this organism. Here we purified to homogeneity the OprM protein, reconstituted it into lipo-somemembranes, and tested its channel activitybyusing the liposome swellingassay. Itwas demonstrated thatOprMis a channel-forming protein and exhibits the channel property that amino acids diffuse more efficiently than saccharides
