Dual mode of gating of voltage-dependent anion channel as revealed by phosphorylation

The single-channel electrophysiological properties of the voltage-dependent anion channel (VDAC) of mitochondria from rat liver have been investigated under normal and phosphorylated (with protein kinase A) conditions. Experi mental observations show that phosphorylation does not affect the current l evel and the opening probability in the positive clamping potentials, but l eads to lowering of current magnitude and opening probability in the negati ve clamping potentials. The opening probability versus voltage (V) plot for native VDAC fits a Gaussian function symmetric around V = 0, whereas the s ame for phosphorylated VDAC fits a linear combination of two Gaussian funct ions. This indicates that there are two gating modes of VDAC; the negative voltage sensor (gate) undergoes modification due to phosphorylation. (C) 20 01 Academic Press.