Mechanosensitive channel that opens in response to stretch forces in the membrane lipid bilayer. Forms a nonselective ion channel with a conductance of about 4 nanosiemens. Participates in the regulation of osmotic pressure changes within the cell. Opens at a pressure just below that which would cause cell disruption and death. The force required to trigger channel opening depends on the membrane lipids composition. Homopentamer. The periplasmic loop between the two transmembrane domains modulates channel kinetics, and in particular the length of time the channel remains in the open conformation. Belongs to the MscL family.