FIG. 1.

ATP-dependent phosphorylation of GST-Crh and GST-CrhS46A. [γ-³²P]ATP and HprK were incubated together with GST-Crh (lane 2) or GST-CrhS46A (lane 3). Lane 1 is the control without GST-Crh or GST-CrhS46A. The phosphorylation reaction was stopped by adding sample buffer to the assay mixtures before loading them onto a sodium dodecyl sulfate-polyacrylamide gel. After electrophoresis, the gel was treated for 5 min with boiling 16% trichloroacetic acid before being dried and exposed to autoradiography (Biomax MR; Kodak). Coomassie blue-stained gels on which the same samples had been loaded revealed a single band for HPr and Crh (data not shown).