Cys-loop receptor

The Cys-loop ligand-gated ion channel superfamily is composed of nicotinic acetylcholine, GABAA, GABAA-ρ, glycine, 5-HT3, and zinc-activated (ZAC) receptors.

Cys-loop receptors are known only in eukaryotes, but are part of a larger family of pentameric ligand-gated ion channels.

Through research done on nicotinic acetylcholine receptors it has been determined that the channels are activated through allosteric interactions between the binding and gating domains.

Once the agonist binds it brings about conformational changes (including moving a beta sheet of the amino-terminal domain, and outward movement from loops 2, F and cys-loop which are tied to the M2-M3 linker and pull the channel open).

Electron microscopy (at 9 Å) shows that the opening is caused by rotation at the M2 domain, but other studies on crystal structures of these receptors has shown that the opening could be a result from a M2 tilt which leads to pore dilation and a quaternary turn of the entire pentameric receptor.