Fig. 3. Two voltage-gating processes in one VDAC channel. The conditions were as in Fig. 1 except that the VDAC channel was isolated from the yeast, S. cerevisiae. The aqueous phase was 1.0 M KCl, 1 mM CaCl2, 5 mM MES pH 5.8. Channel closure occurs at both positive and negative applied voltages. The channels occupy the high-conducting, open, state at low potentials.