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 pHlicKerRE 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.

Extended data Fig 2b-d:  2-IM profiles of beads clamped at indicated pH and [K⁺].

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. 

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 (k) measured from the i-v curve of Fig 6i and 6j.