Abstract
The serotonin (5-hydroxytryptamine; 5-HT) 2A receptor is a cell surface class A G protein-coupled receptor that regulates a multitude of physiological functions of the body and is a target for antipsychotic drugs. Here we found by means of fluorescence resonance energy transfer and immunoprecipitation studies that the 5-HT2A-receptor homodimerized in live cells, which we linked with its antagonist-dependent fingerprint in both binding and receptor signaling. Some antagonists, like the atypical antipsychotics clozapine and risperidone, differentiate themselves from others, like the typical antipsychotic haloperidol, antagonizing these 5-HT2A receptor-mediated functions in a pathway-specific manner, explained here by a new model of multiple active interconvertible conformations at dimeric receptors.
Footnotes
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This work was supported by the Ministerio de Educación y Ciencia, Spain [Grants SAF2007-65913, SAF2005-08025-C03]; the Xunta de Galicia [Grant PGIDIT06PXID203186PR, 2007/118]; and by Red Temática de Investigación Cooperativa COMBIOMED from Instituto de Salud Carlos III and Fundació La Marató de TV3 [Reference 070530].
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J.B., M.C., and J.G. contributed equally to this work.
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ABBREVIATIONS: GPCR, G protein-coupled receptor; 5-HT, 5-hydroxytryptamine, serotonin; AA, arachidonic acid; CHO, Chinese hamster ovary; (±)DOB, (±)-1-(4-bromo-2,5-dimethoxyphenil)-2-aminopropane; (±)DOI, (±)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane; FCS, fetal calf serum; GR55562, (3-[3-(dimethylamino)propyl]-4-hydroxy-N-[4-(4-pyridinyl)phenylbenzamide dihydrobromide]; IP, inositol phosphate; MDL100,907, (R)-(±)-4-[1-hydroxy-1(2,3-dimethoxyphenyl)metyhyl]N-2-4-fluorophenylethyl)piperidine; PLA2, phospholipase A2; PLC, phospholipase C; HEK, human embryonic kidney; MEM, minimum essential medium; PCR, polymerase chain reaction; CFP, cyan fluorescent protein; YFP, yellow fluorescent protein; FRET, fluorescence resonance energy transfer; RIPA, radioimmunoprecipitation assay; PAGE, polyacrylamide gel electrophoresis; TTBS, Tris-buffered saline/Tween 20; compound 40/80, p-methoxy-N-methyl-phenethylamine.
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↵ The online version of this article (available at http://molpharm.aspetjournals.org) contains supplemental material.
- Received December 23, 2008.
- Accepted March 11, 2009.
- The American Society for Pharmacology and Experimental Therapeutics
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