5-Hydroxytryptamine (5-HT, also commonly known as serotonin) is synthesized in enterochromaffin cells in the intestine and in serotonergic nerve terminals. In the periphery, 5-HT mediates gastrointestinal motility, platelet aggregation, and contraction of blood vessels. Many functions of the central nervous system are influenced by 5-HT, including sleep, motor activity, sensory perception, arousal, and appetite. A family of 12 GPCRs and one ion channel mediate the biological effects of 5-HT (Hoyer et al., 1994). 5-HT7 receptor is a Gs-coupled GPCR which is expressed in the heart and brain. Splice variants of the 5-HT7 receptor have been found in the human brain, 5-HT7(a), 5-HT7(b) and 5-HT7(d). Differing only in the lengths of their carboxy terminal, these variants are all functional receptors. GenScript's cloned human 5-HT7-expressing cell line is generated in the 293/CRE-Luc host.