Musset Boris, Decoursey Thomas
Rush Medical Center, molec. biophysics and physiology, DeCoursey, Thomas; Rush Medical Center.
Wiley Interdiscip Rev Membr Transp Signal. 2012 Sep 1;1(5):605-620. doi: 10.1002/wmts.55. Epub 2012 May 11.
The biophysical properties of the voltage gated proton channel (H(V)1) are the key elements of its physiological function. The voltage gated proton channel is a unique molecule that in contrast to all other ion channels is exclusively selective for protons. Alone among proton channels, it has voltage and time dependent gating like other "classical" ion channels. H(V)1 is furthermore a sensor for the pH in the cell and the surrounding media. Its voltage dependence is strictly coupled to the pH gradient across the membrane. This regulation restricts opening of the channel to specific voltages at any given pH gradient, therefore allowing H(V)1 to perform its physiological task in the tissue it is expressed in. For H(V)1 there is no known blocker. The most potent channel inhibitor is zinc (Zn(2+)) which prevents channel opening. An additional characteristic of H(V)1 is its strong temperature dependence of both gating and conductance. In contrast to single-file water filled pores like the gramicidin channel, H(V)1 exhibits pronounced deuterium effects and temperature effects on conduction, consistent with a different conduction mechanism than other ion channels. These properties may be explained by the recent identification of an aspartate in the pore of H(V)1 that is essential to its proton selectivity.
电压门控质子通道（H(V)1）的生物物理特性是其生理功能的关键要素。电压门控质子通道是一种独特的分子，与所有其他离子通道不同，它仅对质子具有选择性。在质子通道中独树一帜的是，它像其他“经典”离子通道一样具有电压和时间依赖性门控。此外，H(V)1是细胞及周围介质中pH值的传感器。其电压依赖性与跨膜pH梯度严格耦合。这种调节将通道的开放限制在任何给定pH梯度下的特定电压，从而使H(V)1能够在其表达的组织中执行其生理任务。对于H(V)1，目前尚无已知的阻滞剂。最有效的通道抑制剂是锌（Zn(2+)），它可阻止通道开放。H(V)1的另一个特点是其门控和电导对温度的强烈依赖性。与短杆菌肽通道那样的单排充满水的孔不同，H(V)1在传导方面表现出明显的氘效应和温度效应，这与其他离子通道的传导机制不同。这些特性可能是由于最近在H(V)1孔中发现了一种对其质子选择性至关重要的天冬氨酸所导致的。
