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. 2012 Jun 20;7(6):e38715. doi: 10.1371/journal.pone.0038715

Figure 3. Ethidium transport in intact cells.

Figure 3

A, ATP-depleted cells expressing Wt LmrP, the mutants K357R, K357A, R260K, or R260A, or no LmrP protein (control) were preloaded with 2 µM ethidium in 50 mM KPi buffer (pH 7.0) containing 5 mM MgSO4. Glucose (25 mM) was added at the time point indicated, to allow the generation of metabolic energy in the cells. The initial rates of active efflux were calculated over the first 20 s during which transport was linear. B, Facilitated ethidium influx in ATP-depleted cells. Ethidium bromide (2 µM) was added at the time point indicated. The initial influx rates were calculated over the first 40 s of linear uptake with the exception of K357A for which the rate was determined over the first 20 s. Data in the main text represent the mean ± SEM of three independent experiments (n = 3). Ethidium transport was measured by fluorimetry.