The neurotransmitter serotonin (5-hydroxytryptamine, 5-HT) has been implicated in a wide range of psychiatric conditions and also has vasoconstrictive and vasodilatory effects. 5-HT5A belongs to the G protein-coupled receptor 1 family. 5-HT5A is also a member of the serotonin receptor family. It is a multi-pass membrane protein that functions as a receptor for 5-hydroxytryptamine and couples to G proteins. 5-HT5A has been shown to function in part through the regulation of intracellular Ca2+ mobilization.