Verification of PsOep23 orientation in a lipid bilayer. The I/V relationship revealed a slightly rectifying current of all open states. This rectification helps to identify the orientation of the channel after fusion with the bilayer, which was randomly distributed. For clarity the large conductance was always allocated to positive holding potentials. The data points represent the average of 16 independent experiments. Electrolyte solution 250 mM KCl, 50 mM Mops/Tris pH 7.0 (symmetrical cis/trans).