In this last section, we compute the electric fields projected along the S4 helices in each domain (Figure ). The vertical motion of these helices triggers transition between the inactivated, closed and open states of the channel. Therefore, the electric fields projected along the S4 helices inform us on the force driving these state transitions. Overall, the system (i.e., Na v 1.7 and solvent and lipids) contributes 11.71 MV/cm, -26.92 MV/cm, -26.45 MV/cm and -38.63 MV/cm to the S4-projected electric field in DI, DII, DIII and DIV, respectively. This means that the environment facilitates S4 in DI to move downwards but S4 in DII, DIII and DIV to move upwards. This is expected in a transition of Na v 1.7 from inactivated to closed state where S4 in DI will be the first helix to move back to a resting position. We find that S4 in DII and DIII experience a similar electric field while S4 in DIV experiences a much stronger field, consistent with a sequential transition to the closed state.