Comparison of E. coli chemotaxis and other two-component systems. In the chemotaxis pathway (left panel) and other two-component systems (right panel), a sensor kinase is activated by a cell-external signal, upon which it autophosphorylates and passes on a phosphoryl group to its response regulator, which typically induces a transcriptional response. The time course of the final output, i.e. gene expression, can be directly mapped onto the binary output of the chemotaxis pathway.
Clausznitzer and Endres BMC Systems Biology 2011 5:151 doi:10.1186/1752-0509-5-151