Prokaryotic Mechanosensitive Channels

Mechanosensitive ion channels are integral membrane proteins that open and close in response to mechanical stress applied either directly to the cell membrane (in the case of intrinsically mechanosensitive channels) or indirectly, through forces applied to other cytoskeletal components. Cellular phenomena mediated by mechanosensitive channels include touch, hearing, cardiovascular tone, detection of gravity, pressure sensation, pain perception, and osmoregulation. Mechanosensirive channels are quite diverse both physiologically and structurally and have been discovered in all fundamental branches of the phylogenetic tree, Eubacteria, Eukarya, and Archaea. Eukaryotic mechanosensitive channels include the TRPV subclass of the Transient Receptor Potential channel family: the TREK-1 and TRAAK members of the two-pore domain potassium channel family K2p; and the DEG/ENaC superfamily composed of degenerins, eptithelial sodium channels, and acid-sensing channels that have been implicated in the touch response of nematodes. Although many of these channels, including the degenerins and the yet-to-be identified channel receptors involved in hearing, appear to have an obligatory requirement for cytoskeletal coupling, others, such as the TREK-1 and TRAAK channels, exhibit intrisinic mechanosensitive activity.