 Similar to other ion channels, MscLs are organized as symmetric oligomers with the permeation pathway formed by the packing of subunits around the axis of rotational symmetry.Unlike MscS, which is heptameric, MscL is likely pentameric; although the Sa-MscL appears to be a tetramer in a crystal structure, this may be an artifact.MscL contains two transmembrane helices that are packed in an up-down/nearest neighbor topology.