DETECTION OF AN INDUCIBLE MEMBRANE PROTEIN ASSOCIATED WITH R-FACTOR-MEDIATED TETRACYCLINE RESISTANCE

New synthesis of an R-factor-specific protein occurs in E. coli minicells containing tetracycline-resistant R factors when they are incubated in the presence of tetracycline. This protein is sometimes detected in small amounts in tetracycline-resistant minicells in the absence of the drug, but it is not detectable in minicells containing R factors which lack tetracycline resistance. The protein has a molecular weight of about 50,000 in sodium dodecyl sulfate (as determined by polyacrylamide gel electrophoresis) and is found preferentially in the minicell membrane. © 1974 Academic Press, Inc.