MscL ion channel protein structure. Molecular model of a mechanosensitive channel of large conductance (MscL) from a Mycobacterium tuberculosis bacterium. MscLs play a critical role in converting physical stress at the cell membrane into an electrochemical response. They respond to larger pressures than the small conductance channels. In prokaryotes such as bacteria, such channels open in response to stretch forces in the membrane and help regulate osmotic pressure within the cell by controlling the passage of ions through it.