Figure. Outer membrane protein (OMP) profiles of Escherichia coli strains. OMP content was determined by using sodium dodecyl sulfate–polyacrylamide gel electrophoresis. Lane 1 corresponds to E. coli CO clinical isolate; lane 2, E. coli JF 568 strain expressing OmpC; lane 3, E. coli JF 701 strain lacking OmpC (9). The molecular mass marker (M) and corresponding sizes (in kilodaltons) are indicated on the left. Horizontal arrows on the right indicate positions of the OMPs OmpF, OmpC, and OmpA.