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