FIG. 2.

Autophosphorylation of MBP-NarX₁₈₅ and MBP-NarQ₁₈₂ with or without an ATP-regenerating system. Labeled proteins were quantified from 5-μl time point samples as described in Materials and Methods. Quantification of phospho-MBP-NarX₁₈₅ (circles) and phospho-MBP-NarQ₁₈₂ (squares) with the addition of an ATP-regenerating system (solid symbols) or without (open symbols) in 100 μM [γ-³²P]ATP (MBP-NarX₁₈₅, 2,300 cpm pmol⁻¹, and MBP-NarQ₁₈₂, 1,800 cpm pmol⁻¹). Specific levels of phosphorylation are expressed as nmol of incorporated phosphate per total amount of protein used, expressed as μmol. Note the change in the x axis scale after 30 min. The data represent one of two independent measurements. Autophosphorylations of MBP-NarX₁₈₅ and MBP-NarQ₁₈₂ were conducted as separate experiments.