Fig. 1.

VDAC was reconstituted into a planar phospholipid membrane composed of 0.5% PC, 0.5% asolectin and 0.05% cholesterol in the presence of 1.0 M KCl, 20mM HEPES, pH=7.2. 0.4mM EGTA was then added to each side of the chamber to chelate any possible trace amount of Ca²⁺. 2mM Ca²⁺ was added later to compare VDAC’s gating in the presence and absence of Ca²⁺. (Note: there is enough buffer to control the pH even after acid is released following chelation of some Ca²⁺) VDAC’s gating was recorded by applying 50 mV (cis side is ground). The total conductance in the absence and presence of Ca²⁺ is 115 nS and 179 nS, respectively. There is an 18-minute gap between these records and the conductance increased because of VDAC insertion. The percent conductance drop and the rate of decay are essentially the same with and without free Ca²⁺.