Fig. 1: Activating the pore of animal Cys-loop receptors with protons.
From: Disentangling the mechanistic role of loop-C capping in Cys-loop receptor activation
a Membrane-threading pattern common to all Cys-loop-receptor subunits. The ECD is shown in cyan, and the TMD, in gray. b Amino-acid sequences at either side of the domain–domain junction of the seven ECD–TMD chimeras tested here. The two chimeras that gave rise to the largest macroscopic currents—and thus, those for which the effect of deleting all five loops C on function was studied—are indicated with a dashed-line rectangle. c Atomic model of a Cys-loop receptor (agonist-bound desensitized human α7 AChR; PDB ID 7KOQ7). One of the subunits is color-coded on the basis of secondary structure (α-helix: orange; β-strand: yellow; 310-helix: blue; turn: dark cyan; and coil: red)59, and the molecule of bound orthosteric agonist (epibatidine) is colored purple. The molecular images were made with Visual Molecular Dynamics (VMD57) using cartoon representation for the protein and surface representation for the agonist. For the sake of clarity, the C-terminal tail of the highlighted subunit was omitted, and the intracellular portion of the channel is not shown.
