Cloning and functional expression of a human 5-hydroxytryptamine type 3AS receptor subunit

Delia Belelli, Joanna M. Balcarek, Anthony G. Hope, John A. Peters, Jeremy J. Lambert, Thomas P. Blackburn

Research output: Contribution to journalArticle

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Abstract

A human 5-hydroxytryptamine receptor type 3AS (5-HT3R-AS) subunit has been cloned from an amygdala cDNA library. We report the nucleotide and predicted amino acid sequence of the human subunit, which possesses 85% and 84% amino acid sequence identity with mouse and rat 5-HT3R-AS subunits, respectively. Acting on Xenopus laevis oocytes injected with RNA transcripts of the clone, 5-HT and selective 5-HT3 receptor agonists elicited inwardly directed current responses that displayed desensitization. Such currents were blocked in a concentration-dependent manner by selective and nonselective 5-HT3 receptor antagonists but were unaffected by compounds acting at G protein-linked 5-HT receptors. A quantitative comparison of the pharmacological profiles of human and mouse recombinant 5-HT3R-AS receptor complexes revealed differences in the potencies of some antagonist or agonist compounds tested, the most dramatic example being (+)-tu-bocurarine, which demonstrated an ∼ 1800-fold discrepancy in antagonist potency. In view of the small number of sequence substitutions that occur between the human and mouse homo-logues of the 5-HT3R-AS in the extracellularly located aminoterminal domain, compounds such as (+)-tubocurarine, in conjunction with site-directed mutagenesis, may prove to be valuable in locating amino acid residues that contribute to the ligand binding site(s) of the 5-HT3 receptor. Also, when methodological differences are taken into account, the present study suggests that a homo-oligomeric assembly of human 5-HT3R-AS subunits can account for the distinctive ligand binding properties of human 5-HT3 receptors established in postmortem brain tissue.

Original languageEnglish
Pages (from-to)1054-1062
Number of pages9
JournalMolecular Pharmacology
Volume48
Issue number6
Publication statusPublished - 1 Dec 1995

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Serotonin Receptors
Organism Cloning
Receptors, Serotonin, 5-HT3
Amino Acid Sequence
Serotonin 5-HT3 Receptor Agonists
Ligands
Serotonin 5-HT3 Receptor Antagonists
Tubocurarine
Xenopus laevis
Site-Directed Mutagenesis
Amygdala
Gene Library
GTP-Binding Proteins
Oocytes
Serotonin
Nucleotides
Clone Cells
Binding Sites
Pharmacology
RNA

Cite this

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abstract = "A human 5-hydroxytryptamine receptor type 3AS (5-HT3R-AS) subunit has been cloned from an amygdala cDNA library. We report the nucleotide and predicted amino acid sequence of the human subunit, which possesses 85{\%} and 84{\%} amino acid sequence identity with mouse and rat 5-HT3R-AS subunits, respectively. Acting on Xenopus laevis oocytes injected with RNA transcripts of the clone, 5-HT and selective 5-HT3 receptor agonists elicited inwardly directed current responses that displayed desensitization. Such currents were blocked in a concentration-dependent manner by selective and nonselective 5-HT3 receptor antagonists but were unaffected by compounds acting at G protein-linked 5-HT receptors. A quantitative comparison of the pharmacological profiles of human and mouse recombinant 5-HT3R-AS receptor complexes revealed differences in the potencies of some antagonist or agonist compounds tested, the most dramatic example being (+)-tu-bocurarine, which demonstrated an ∼ 1800-fold discrepancy in antagonist potency. In view of the small number of sequence substitutions that occur between the human and mouse homo-logues of the 5-HT3R-AS in the extracellularly located aminoterminal domain, compounds such as (+)-tubocurarine, in conjunction with site-directed mutagenesis, may prove to be valuable in locating amino acid residues that contribute to the ligand binding site(s) of the 5-HT3 receptor. Also, when methodological differences are taken into account, the present study suggests that a homo-oligomeric assembly of human 5-HT3R-AS subunits can account for the distinctive ligand binding properties of human 5-HT3 receptors established in postmortem brain tissue.",
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Cloning and functional expression of a human 5-hydroxytryptamine type 3AS receptor subunit. / Belelli, Delia; Balcarek, Joanna M.; Hope, Anthony G.; Peters, John A.; Lambert, Jeremy J.; Blackburn, Thomas P.

In: Molecular Pharmacology, Vol. 48, No. 6, 01.12.1995, p. 1054-1062.

Research output: Contribution to journalArticle

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AU - Blackburn, Thomas P.

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