5-Hydroxytryptamine2-family receptors (5-hydroxytryptamine2A, 5-hydroxytryptamine2B, 5-hydroxytryptamine2C): where structure meets function.
5-Hydroxytryptamine2 (serotonin2, 5-HT2)-family receptors are important for mediating many physiological functions, including vascular and nonvascular smooth muscle contraction, platelet aggregation, modulation of perception, mood, anxiety, and feeding behavior. A large number of psychopharmaceuticals, including atypical antipsychotic drugs, antidepressants, anxiolytics, and hallucinogens, mediate their actions, at least in part, via interactions with various 5-HT2-family receptors. This review article summarizes information about structure-function aspects of 5-HT2-family receptors. Evidence is presented that implies that conserved aromatic and charged residues are essential for ligand binding to 5-HT2A receptors. Additionally, findings are reviewed that are consistent with the hypothesis that residues located in intracellular loops 2 and 3 (i2 and i3) mediate coupling to specific G(alpha)-subunits such as G(alpha q). Studies are reviewed that suggest that 5-HT2-family receptors may be down-regulated by both agonists and antagonists, and usually this down-regulation is due to post-transcriptional mechanisms. Finally, a model for regulation of 5-HT2-family receptors by receptor-mediated endocytosis is advanced, and the particular structural features responsible for the various endocytotic pathways are emphasized. Taken together, these results suggest that discrete domains of the receptor structure are important for ligand binding, G-protein coupling, and internalization.
Department of Psychiatry, Case Western Reserve University Medical School, Cleveland, OH 44106-4935, USA.
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Roth
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Willins
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Kristiansen
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Kroeze
D000595:Amino Acid Sequence; D016166:Free Radical Scavengers / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D011985:Receptors, Serotonin / Q000737:chemistry / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism*; D018490:Serotonin Agents / Q000493:pharmacokinetics*
D016166:Free Radical Scavengers; D011985:Receptors, Serotonin; D018490:Serotonin Agents; D012701:Serotonin