Voltage-gated Kv7 (or KCNQ) channels play a pivotal role in controlling membrane excitability. Like typical voltage-gated ion channels, Kv7 channels undergo a closed-to-open transition by sensing changes in transmembrane potential, and thereby mediate inhibitory K+ currents to reduce membrane excitability. Reduction of Kv7 channel activity as a result of genetic mutation is responsible for various human diseases due to membrane hyperexcitability, including epilepsy, arrhythmia and deafness. As a result, the discovery of small compounds that activate voltage-gated ion channels is an important strategy for clinical intervention in such disorders. Because ligand binding can induce a conformational change leading to subthreshold channel opening, there is considerable interest in understanding the molecular basis of these 'gain-of-function' molecules. Although small-molecule activators of cation channels are rare, several novel compounds that activate Kv7 voltage-gated channels have been identified. Recent advances in defining the activator-binding sites and in understanding their mechanism of action have begun to provide insight into the activation of voltage-gated channels by synthetic compounds.
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