Schematic of hERG channel PAS-CNBHD interaction and role of the intrinsic ligand. (A) WT hERG channels showing the intrinsic ligand with intrinsic ligand residues FNL in the CNBHD and the PAS-CNBHD interaction. (B) Depiction of a hERG channel with the F860G,L862G double mutant in the intrinsic ligand showing a disruption of the PAS-CNBHD interaction. Two hERG subunits (of four) are shown for clarity.