The serotonin binding site of human and murine 5-HT 2B receptors. Molecular modeling and site-directed mutagenesis

Philippe Manivet, Benôt Schneider, Jeremy Christopher Smith, Doo Sup Choi, Luc Maroteaux, Odile Kellermann, Jean Marie Launay

Research output: Contribution to journalArticlepeer-review

68 Scopus citations

Abstract

Bacteriorhodopsin and rhodopsin crystal structures were used as templates to build structural models of the mouse and human serotonin (5-HT)-2B receptors (5-HT 2BRs). Serotonin was docked to the receptors, and the amino acids predicted to participate to its binding were subjected to mutagenesis. 5-HT binding affinity and 5-HT-induced inositol triphosphate production were measured in LMTK - cells transfected with either wild-type or mutated receptor genes. According to these measurements, the bacteriorhodopsin-based models of the 5-HT 2BRs appear more confident than the rhodopsin-based ones. Residues belonging to the transmembrane domains 3 and 6, i.e. Asp 3.32, Ser 3.36, Phe 6.52, and Asn 6-55, make direct contacts with 5-HT. In addition, Trp 3.28, Phe 3.35, Phe 6.52, and Phe 7.38 form an aromatic box surrounding 5-HT. The specificity of human and mouse 5-HT 2BRs may be reflected by different rearrangements of the aromatic network upon 5-HT binding. Two amino acids close to Pro 5.50 in the human transmembrane domain 5 sequence were permuted to introduce a "mouse-like" sequence. This change was enough to confer the human 5-HT 2BR properties similar to those of the mouse. Taken together, the computed models and the site-directed mutagenesis experiments give a structural explanation to (i) the different 5-HT pK D values measured with the human and mouse 5-HT 2BRs (7.9 and 5.8, respectively) and (ii) the specificity of 5-HT binding to 5-HT 2BRs as compared with other serotonergic G-protein coupled receptors.

Original languageEnglish (US)
Pages (from-to)17170-17178
Number of pages9
JournalJournal of Biological Chemistry
Volume277
Issue number19
DOIs
StatePublished - May 10 2002

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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