5-hydroxytryptamine receptor 4 (5-HT4 receptors) are a subclass among the large family of receptors mediating serotonin actions at central and peripheral targets. 5-HT4 receptor activation has been implicated in learning and memory, feeding control and stress response. 5-HT4 receptors are encoded by a complex gene which in humans, generates ten different splice variants.The 5-HT4 receptor, a member of the seven transmembrane spanning G-protein-coupled receptors (GPCRs), couples via Gs to increase cAMP production. GPCRs share a similar topology, with seven transmembrane helices (TMHs) connected by three extracellular loops (ECLs), and three intracellular loops (ICLs); the N-terminus is on the extracellular side of the membrane, and the C-terminus is on the cytoplasmic side
