PAS domains: internal sensors of oxygen, redox potential, and light

PAS domains are signaling domains distributed in proteins from members of the Archeae and Bacteria and from fungi, insects, plants, and vertebrates. The domains function as input modules in proteins that sense redox potential, oxygen, light and other types of stimuli. PAS proteins are located intracellular and observes external and internal environments. The transduction of redox signal may be a common mechanistic theme in several PAS domains.