Characterization of the naturally occurring Arg344His variant of the human 5-HT3A receptor
| Autor: | Arevat Kostanian, Jutta Walstab, Heinz Bönisch, Sandra Combrink, Michael Brüss, Manfred Göthert, Martin Barann |
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| Rok vydání: | 2009 |
| Předmět: |
Patch-Clamp Techniques
B-cell receptor Biology Cell Line Beta-1 adrenergic receptor Radioligand Assay Aequorin Muscarinic acetylcholine receptor M5 Radioligand Enzyme-linked receptor Humans Receptor Protease-activated receptor 2 5-HT receptor Pharmacology Binding Sites Cell Membrane Genetic Variation General Medicine Molecular biology Serotonin Receptor Agonists Electrophysiology Luminescent Measurements Schizophrenia Calcium Serotonin Antagonists Receptors Serotonin 5-HT3 |
| Zdroj: | Pharmacological Reports. 61:785-797 |
| ISSN: | 1734-1140 |
| DOI: | 10.1016/s1734-1140(09)70134-3 |
| Popis: | The present study aimed at examining the function and pharmacological properties of the naturally occurring Arg344His variant of the human 5-HT(3A) receptor, identified in a schizophrenic patient. In intact human embryonic kidney (HEK) 293 cells expressing the wild-type (WT) or the variant receptor, the function was analyzed by indirect measurement of agonist-induced Ca(2+) current through the 5-HT(3A) receptor channel by an aequorin luminescence-based Ca(2+) assay. In cell membrane patches cation currents were determined electrophysiologically including technically demanding single channel analyses. The pharmacological properties were analyzed by [(3)H]GR65630 binding to cell membrane fragments. The density of [(3)H]GR65630 binding sites in cells expressing the variant receptor was reduced to 55% of that in cells expressing the WT receptor, which, however, was not accompanied by an analogous decrease in 5-HT-induced Ca(2+) influx through the receptor channel. However, the single channel analysis suggests an increase in single receptor channel mean open time (which is known to be subject of many variables) but not in unitary current amplitude. Radioligand competition experiments revealed that the affinity of five 5-HT(3) receptor agonists and four antagonists for the variant receptor did not differ from that for the WT receptor. In conclusion, the variant receptor resembles the WT receptor in that it forms functional homopentameric 5-HT(3A) receptors with identical pharmacological properties. In view of the lack of reduction in Ca(2+) flux through the variant receptor channels in spite of the decrease in its density on the cell membrane, the increase in single receptor channel mean open time appears to compensate for the reduction in variant receptor density. |
| Databáze: | OpenAIRE |
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