A highly charged voltage-sensor helix spontaneously translocates across membranes.

Moving freely: A recent model for voltage gating of potassium channels proposed that the four arginine residues of the voltage-sensing S4 helix (left) are in direct contact with the membrane lipids and move into the hydrocarbon core of the membrane during gating. It is demonstrated that the physical properties of the isolated S4 sequence (right) are sufficient to allow it to freely translocate across synthetic membranes.