 Therefore, when the membrane is stretched, MscL will experience a pull mostly concentrated in the interfacial regions.Mutations that effect protein-lipid interactions near the interfaces result in loss-of-function phenotypes.The tension applied to the inner and outer rims of the channel by the lipid bilayer tilts the transmembrane helixes of MscL (The tilts of the M1 helices change by 35-34o during the transition), causing a gradual iris-like expansion and flattening of the MscL barrel.