Molecular structures of the postulated binding poses predicted by covalent docking calculations. (A) MTS-TAMRA docked at depolarized spHCN^R332C (left) and hyperpolarized spHCN^R332C (right), with insets showing predicted 2-D ligand interaction diagrams. (B) ALEXA-488 docked at depolarized spHCN^R332C (left) and hyperpolarized spHCN^R332C (right), with insets showing close-up rendering of the fluorophore interacting with either extracellular water (left) or lipid tails (right). One subunit of spHCN^R332C is represented by ribbons, with S4 in red, S5 in green, and S6 in yellow. Fluorophores are shown as large brightly colored spheres, bilayer phosphorus atoms are shown in bronze to illustrate the demarcation between the water and lipid phases. For the ligand interaction diagrams, residues in green are hydrophobic, residues in blue are polar, and fluorophore atoms exposed to solvent are shown by a cloud.