Fig. 4.

Motor-remodeling cartoon. (A) Binding sites in a motor of a cheR cheB cell are shown. At high CheY-P levels, a large number of CheY-P molecules bind, and the motor rotates CW. The motor contains a small steady-state FliM population, and the exchanging fraction of FliM is in the majority. (B) Upon addition of attractant, CheY-P levels fall, so fewer CheY-P molecules bind, and the motor switches to CCW. Most of the FliM molecules initially bound to the motor now bind more strongly, due to structural changes accompanying the switch to CCW rotation. (C) The exchanging population evolves to a new steady state, leading to a growth in the total FliM content. This growth enhances the probability of CheY-P binding to the motor. (D) The motor now contains a larger steady-state FliM population: The motor has partially adapted and is able to switch.