Multicellular organisms must be able to adapt to cellular events to accommodate prevailing conditions. Sensory-response circuits operate by making use of a phosphorylation control mechanism known as the "two-component system." This volume, the third in a three-volume treatment edited by the same group of editors, includes a wide range of methods, including those dealing with the Sln-1 kinase pathway, triazole sensitivity in C. albicans, and histidine kinases in cyanobacteria circadian clock.