Side pockets provide the basis for a new mechanism of Kv channel–specific inhibition

Abstract

Most known small-molecule inhibitors of voltage-gated ion channels have poor subtype specificity because they interact with a highly conserved binding site in the central cavity. Using alanine-scanning mutagenesis, electrophysiological recordings and molecular modeling, we have identified a new drug-binding site in Kv1.x channels. We report that Psora-4 can discriminate between related Kv channel subtypes because, in addition to binding the central pore cavity, it binds a second, less conserved site located in side pockets formed by the backsides of S5 and S6, the S4–S5 linker, part of the voltage sensor and the pore helix. Simultaneous drug occupation of both binding sites results in an extremely stable nonconducting state that confers high affinity, cooperativity, use-dependence and selectivity to Psora-4 inhibition of Kv1.x channels. This new mechanism of inhibition represents a molecular basis for the development of a new class of allosteric and selective voltage-gated channel inhibitors.

Protein Kinase A–Phosphorylated K V 1 Channels in PSD95 Signaling Complex Contribute to the Resting Membrane Potential and Diameter of Cerebral Arteries

“…16, 17 In this regard, Shab -type K V 2 channels and KCNQ (K v 7) channels likely contribute to the Psora4-insensitive residual current. Stromatoxin-sensitive K V 2 channels are not blocked by Psora4 in cVSMCs 16, 35 and Psora4 does not compromise vasoconstrictor responses of CA to the K V 7 channel blocker, linopirdine (Online Figure VI). …”

“…A second scrambled control peptide (Scm2) also did not significantly constrict CA (Online Figure III). Bath application of the K V 1 channel blocker, 5-(4-phenylalkoxypsoralen) (Psora4) 2, 16, 34, 35 did not further reduce the diameter of arteries already constricted by K V 1-C peptide (Figures 3C-D). Notably, the constrictor response to 100 nmol/L Psora4 was not different from the constriction caused by 10 µmol/L K V 1-C peptide (Figure 3D) or the diameter change induced by combined Psora4 and K V 1-C peptide (Figure 3D).…”

“…Accordingly, control K + currents were recorded from cVSMCs dialyzed with either 3 µmol/L Scm NP (Figure 6A) or 3 µmol/L K V 1-C NP (Figure 6B) before addition of the selective K V 1 channel blocker, 100 nmol/L Psora4. 2, 16, 34, 35 Digital subtraction of post-Psora4 (+Psora4) from pre-Psora4 (−Psora4) recordings provided an estimation of Psora4-sensitive K V 1 current (Figure 6C, I Psora ). The residual currents were regarded as Psora4-insensitive (Figure 6D, I other ).…”

Modulation of Kv2.1 channels inactivation by curcumin

“…Kv2.1 channels function by altering the membrane properties, as 283 was previously suggested [18], although we cannot discard the 284 binding of curcumin in another region different of the pore in the 285 channel, as is the case of the binding of Psora-4 in the side pockets 286 of Kv1 channels [33]. 287…”

Therapeutic manipulation of the ductus arteriosus: current options and future prospects

“…31 In this context, a recent work pointing to the possible design of a selective inhibitor for the sensor-linked potassium channel, K V 1.5, is worth noting. 64 In other words, several options are at hand to meet this particular challenge.…”