Figure 3.

BrET interacts directly with Shaker-VSD. (a) Chemical structure of BrET is shown. (b) Binding curve was generated from NMR titration of BrET with the Shaker-VSD. The BrET ¹H NMR spectra used to generate this curve are shown in Fig. S8. (c) The addition of BrET to the isolated Shaker-VSD causes a localized perturbation of the three-dimensional TROSY-HNCO NMR spectrum, indicating a specific binding interaction. The normalized change in peak volume in the Shaker-VSD upon BrET binding is plotted on a homology model of the isolated Shaker-VSD with a blue to red color scale as shown. Significant peak volume reduction is observed for residues from S2 transmembrane helix. Small chemical shift perturbations are also observed, as shown in Fig. S7.