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. 2001 May 15;98(11):6068–6073. doi: 10.1073/pnas.111139698

Figure 3.

Figure 3

Time courses of active lactose transport by E. coli T184 (ZY+) or downhill lactose translocation by E. coli HB101 (Z+Y) expressing wild-type permease, mutants R302A and R302S, no permease (pT7–5 vector only), or mutant E325A. Cells were grown at 37°C, and aliquots of cell suspensions (50 μl, containing ≈35 μg of protein in 100 mM KPi, pH 7.5/10 mM MgSO4) were assayed at 0.4 mM final external lactose concentrations as described in Experimental Procedures. For downhill assays with E. coli HB101, 20 μM CCCP was included to abolish the H+ electrochemical gradient.