Pharmacological augmentation of neuronal KCNQ muscarinic (M) currents by drugs such as retigabine (RTG) represents a first-in-class therapeutic to treat certain hyperexcitatory diseases by dampening neuronal firing. Whereas all five potassium channel subtypes (KCNQ1-KCNQ5) are found in the nervous system, KCNQ2 and KCNQ3 are the primary players that mediate M currents. We investigated the plasticity of subtype selectivity by two M current effective drugs, retigabine and zinc pyrithione (ZnPy). Retigabine is more effective on KCNQ3 than KCNQ2, whereas ZnPy is more effective on KCNQ2 with no detectable effect on KCNQ3. In neurons, activation of muscarinic receptor signaling desensitizes effects by retigabine but not ZnPy. Importantly, reduction of phosphatidylinositol 4,5-bisphosphate (PIP 2 ) causes KCNQ3 to become sensitive to ZnPy but lose sensitivity to retigabine. The dynamic shift of pharmacological selectivity caused by PIP 2 may be induced orthogonally by voltagesensitive phosphatase, or conversely, abolished by mutating a PIP 2 site within the S4-S5 linker of KCNQ3. Therefore, whereas drugchannel binding is a prerequisite, the drug selectivity on M current is dynamic and may be regulated by receptor signaling pathways via PIP 2 . . They open at subthreshold voltages and the channel activity is functionally down-regulated by G protein coupled receptor (GPCR) signaling pathways through intracellular secondary messengers, primarily phosphatidylinositol 4,5-bisphosphate (PIP 2 ) (1, 2). In the nervous system, KCNQ2 and KCNQ3 subtypes are major determinants for potassium current sensitive to muscarinic (M) receptor signaling, hence also known as M current (3). The combination of sensitivity to subthreshold voltages and down-regulation by receptor signaling makes M current a critical component for controlling membrane potential in the nervous system, and consequently neuronal firing (4-6). KCNQ2-5 channels, with few exceptions (7), are primarily expressed in the brain and peripheral nervous system. KCNQ1, although it is found in brain (8), is more abundantly expressed in the heart to mediate slow delayed rectifier K + current (also known as I Ks ) that contributes to the termination of action potential, hence regulating QT duration (9).Retigabine (RTG) or ethyl N-[2-amino-4-[(4-fluorophenyl) methylamino] phenyl]carbamate, a positive allosteric modulator (or an opener) for neuronal KCNQ channel, is a first-in-class therapeutic for antiepileptic treatment (10-12). Its clinical use to dampen the hyperexcitatory activity has greatly intensified the interest in a more detailed understanding of chemical augmentation of voltage-sensitive channel activity. Retigabine has selectivity for KCNQ2, -3, -4, and -5 potassium channels but not KCNQ1 potassium channels (13). Tryptophan (W) 236 in KCNQ2 is conserved among the sensitive channels. Interestingly, KCNQ2 channels with W236L mutation (or KCNQ2 W236L ) are functional but no longer sensitive to retigabine (14,15). This and other evidence supports the idea that W236 is a ...