FIG. 5.

Effects of ADP on the accumulation of radiolabeled MBP-NarX₁₈₅ (A) and MBP-NarQ₁₈₂ (B) in 30 nM [γ-³²P]ATP (MBP-NarX₁₈₅, 3,000 cpm fmol⁻¹, and MBP-NarQ₁₈₂, 7,000 cpm fmol⁻¹). At the time points shown, 5-μl samples of radiolabeled protein were quantified as described in Materials and Methods. Specific levels of phosphorylation are expressed as pmol of incorporated ³²P per total amount of protein used, expressed as μmol. Immediately following the removal of the 4-min sample, different concentrations of ADP were added to the reaction mixture (arrows) with the following final concentrations: 1× standard buffer (solid squares), 0.1 μM ADP (diamonds), 1 μM ADP (triangles), and 10 μM ADP (open squares). The data represent one of two independent measurements.