Figure 3: Putative binding mode of AC-1.

(a) Inhibition of wt and mutant Kv7.1/KCNE1 channels by 300 nM AC-1. Influence of amino acid exchange (yellow) on channel sensitivity to 300 nM AC-1 was investigated using alanine scanning combined with TEVC. Inhibition was determined as percent change in current amplitude at the end of a depolarizing test pulse (n=4–57, ±s.e.m.; one way analysis of variance, Dunnett’s post hoc test; ***P<0.001). (b) Cartoon of a single Kv7.1 channel subunit with scanned region in yellow. The circles indicate positions of mutations that significantly alter AC-1 sensitivity (key residues). Magenta filled circles indicate residues that face into the fenestration and blue filled circles mark residues that do not face fenestrations. (c) A preopen closed state model of Kv7.1/KCNE1 (Kv7.1 colored blue, KCNE1 colored yellow) with key residues highlighted in magenta (fenestration facing), blue non-fenestration facing and orange (fenestration facing in KCNE1). (d) Molecular docking of AC-1 to a homology model of Kv7.1/KCNE1 (ref. 33). AC-1 was positioned in close proximity to the amino acid residues identified by alanine scanning. AC-1 is located in a fenestration, which is only formed in the presence of KCNE1 (ref. 35).