ABSTRACT
Ligand-gated ion channels are integral glycoproteins that transverse the cell membrane. All molecularly characterized ligand-gated ion channels are multisubunit complexes. Ligand-gated ion channels generally exist in one of three functional states: resting (or closed), open, or desensitized. Each functional state may reflect many discrete conformational states with different pharmacological properties. Receptors in the resting state, upon application of agonist, will undergo a fast transition to the open state, called
gating
, and most agonists will also undergo a transition to the desensitized state. Because the desensitized state often exhibits higher agonist affinity than the open state, most of the receptors will be in the desensitized state after prolonged agonist exposure.
