Extended data figures

Extended data Fig 1b: Excitation and emission spectra of TAC-Rh with increasing K⁺ concentration at pH = 7.0. Extended data Fig 1c: Normalized O/R ratio of TAC-Rh/Alexa Fluor 647 with increasing [K⁺] at pH 7.0 and 6.0. Extended data Fig 1d: Fluorescence emission spectra of <em>pHlicKerRE</em> corresponding to TAC-Rh and Alexa Fluor 647 with increasing [K+] at pH = 7.0. Extended data Fig 1e: Normalized O/R ratio of TAC-Rh/Alexa Fluor 647 with increasing [K⁺] at pH 7.0. <br> Extended data Fig 2b-d: 2-IM profiles of beads clamped at indicated pH and [K⁺]. <br> Extended data Fig 4b: Normalized whole cell intensities for the uptake of Alexa 647 labelled 3W^EE in untransfected and hMSR1 transfected HEK 293T cells. Extended data Fig 4c: Normalized intensities for HEK 293T cells pulsed with 3W^RE in the presence (+Tf) and absence (-Tf) of Tf. <br> Extended data Fig 5a: Representative families of currents measured from cells stably expressing WT-Kv_11.1 or G601S- Kv_11.1 channel proteins (traces recorded using the standard extracellular saline). Extended data Fig 5b: Representative families of currents measured from cells stably expressing WT-Kv_11.1 or G601S- Kv_11.1 channel proteins (traces recorded using modified extracellular saline). Extended data Fig 5c: Midpoint potential for IKv_11.1 activation (V_1/2) measured from the i-v curve of Fig 6i and 6j. Extended data Fig 5d: Slope factor for IKv_11.1 current activation (<em>k</em>) measured from the i-v curve of Fig 6i and 6j. <br>