FIG. 3.

Ethidium transport in HorA-expressing cells and nonexpressing cells of L. lactis. Panel (A) De-energized HorA-expressing and control cells (0.2 mg of protein/ml; OD₆₉₀, 0.5) were preequilibrated with 10 μM ethidium bromide at 30°C. The development of fluorescence of the DNA-ethidium complex in the cell suspension was monitored at 20°C over time. At the arrow, 25 mM glucose was added. (B) Effect of ortho-vanadate on the accumulation of ethidium bromide in control cells. Cells were energized with arginine and incubated for 7.5 min in the presence or absence of 0.5 mM ortho-vanadate prior to the addition of 10 μM ethidium bromide (at the arrow). (C) Effect of ortho-vanadate on the accumulation of ethidium bromide in HorA-expressing cells. Cells were treated as described for panel B.