FIG. 3.

Phosphotransfer between sensor kinase CbbSR^R96 and response regulator CbbRR1 (wild-type and wild-type plus D54N, H171D, and D54NH171D mutant CbbRR1 proteins) (A) and response regulator CbbRR2 (wild-type and wild-type plus D54N, D195N, and D54ND195N mutant CbbRR2) (B). A total of 380 pmol of sensor kinase was preincubated with 20 μM [γ-³²P]ATP for 20 min (far left lanes) before the addition of approximately 1 nmol of each response regulator, and the reaction mixture was incubated at room temperature for 1 h.