FIGURE 7.

In vitro phosphorylation of Bce module proteins. Purified, detergent-solubilized BceS-His₈ was mixed in equimolar ratios with BceAB, BceR, or both as indicated on the left. A, phosphorylation was started at t = 0 min by adding [γ-³²P]ATP. At the indicated times, reactions were stopped; the samples were subjected to SDS-PAGE, and phosphorylated proteins were detected by phosphorimaging. Representative autoradiographs of three to four independently performed experiments are shown. B and C, band intensities of BceS-³²P (B) and BceR-³²P (C) were quantified and plotted over time. The protein combinations in each assay are given on the right by the last letter of their names. Data are shown as the mean ± S.D. of three to four independently performed experiments.