Comparing between these two regions, the N-terminus clearly inserts further into the membrane, with residues F15 and L11 reaching almost 1nm beneath the membrane surface. The W238 and F241 residues, by comparison, are found to only somewhat penetrate into the hydrophobic membrane core. In this pose, the opening of the S2 active site is pointed down towards the membrane and held near the membrane surface, potentially facilitating ingress of additional IPP molecules to extend the prenyl chain.