These proteins are predicted to have 12
alpha-helical transmembrane regions, some of the animal proteins may have an additional
C-terminal helix. The X-ray structure of the NorM was determined to 3.65 Å, revealing an outward-facing conformation with two portals open to the outer leaflet of the membrane and a unique topology of the predicted 12 transmembrane helices distinct from any other known multidrug resistance transporter. == Discovery ==