Dill E T, Holden M J, Colombini M
Department of Zoology, University of Maryland, College Park 20742.
J Membr Biol. 1987;99(3):187-96. doi: 10.1007/BF01995699.
The mitochondrial outer membrane contains voltage-gated channels called VDAC that are responsible for the flux of metabolic substrates and metal ions across this membrane. The addition of micromolar quantities of aluminum chloride to phospholipid membranes containing VDAC channels greatly inhibits the voltage dependence of the channels' permeability. The channels remain in their high conducting (open) state even at high membrane potentials. An analysis of the change in the voltage-dependence parameters revealed that the steepness of the voltage dependence decreased while the voltage needed to close half the channels increased. The energy difference between the open and closed states in the absence of an applied potential did not change. Therefore, the results are consistent with aluminum neutralizing the voltage sensor of the channel. pH shift experiments showed that positively charged aluminum species in solution were not involved. The active form was identified as being either (or both) the aluminum hydroxide or the tetrahydroxoaluminate form. Both of these could reasonably be expected to neutralize a positively charged voltage sensor. Aluminum had no detectable effect on either single-channel conductance or selectivity, indicating that the sensor is probably not located in the channel proper and is distinct from the selectivity filter.
线粒体外膜含有名为电压依赖性阴离子通道（VDAC）的电压门控通道，这些通道负责代谢底物和金属离子穿过该膜的通量。向含有VDAC通道的磷脂膜中添加微摩尔量的氯化铝会极大地抑制通道通透性的电压依赖性。即使在高膜电位下，通道仍保持在高传导（开放）状态。对电压依赖性参数变化的分析表明，电压依赖性的陡度降低，而关闭一半通道所需的电压增加。在没有施加电位的情况下，开放状态和关闭状态之间的能量差没有变化。因此，结果与铝中和通道的电压传感器一致。pH值变化实验表明，溶液中带正电荷的铝物种不参与其中。活性形式被确定为氢氧化铝或四羟基铝酸盐形式（或两者皆是）。可以合理预期这两种形式都能中和带正电荷的电压传感器。铝对单通道电导或选择性均无可检测到的影响，这表明传感器可能不在通道本身，且与选择性过滤器不同。
