FIG. 7.

Adaptation systems. A flowchart of the possible means of adaptation is shown. The almost universal methylation-dependent adaptation system is shown on the left. The less highly conserved methylation-independent pathways are on the right. We speculate here that CheV might directly influence CheA activity following phosphorylation, as shown, while the means of CheC activation and adaptational action are not yet understood. Black diamonds represent a chemoeffector. Adaptational proteins are hatched; excitatory proteins are shaded.