ABSTRACT
5-HT3 receptors are distributed throughout the nervous system, although they have particular importance in brain areas involved in the vomiting reflex and in the gastrointestinal tract. The high-resolution structures of 5-HT3 receptors have been determined, and show the classic pentameric ligand-gated ion channel (LGIC) pattern of five subunits surrounding a central pore. There are five known subunits (A–E), with splice variants and posttranslational modifications increasing potential variability. Receptor activation results in opening of a cation-selective channel and can be modulated by neuroactive compounds; some of these are useful as therapeutics, e.g., 5-HT3 receptor antagonists are potent antiemetics.
