FIG. 5.

Gel retardation experiments. The radioactive ³²P-labeled aotJ operator DNA fragment was incubated with various ArgR concentrations in the absence of l-arginine. The reactions were terminated by the addition of excess unlabeled operator DNA and applied to a 5% polyacrylamide gel while the gel was running. Lanes 1 to 9 contained ArgR concentrations of 0, 1, 3, 6, 12, 26, 50, 100, and 200 pM, respectively.