About the cover

September 2011 Volume 7 No 9

Non-natural amino acids with different electrostatic surface potentials (as depicted on the cover as a color gradient) into the Shaker voltage-sensing potassium channel were introduced by nonsense suppression mutagenesis by Pless et al. to find that salt bridges are not necessary during channel gating, but rather, two of the acidic residues may occupy a hydrophilic water-filled vestibule that creates an energetically favorable environment for movement of positive charges during channel gating. Cover art by Erin Dewalt, based on images from Christopher Ahern.