Pharmacological characterization of the cloned human 5-hydroxytryptamine transporter.
We performed an extensive pharmacological study of the 5-hydroxytryptamine (5-HT) transporter polypeptide cloned from human placenta. Transient expression of this 630 amino acid polypeptide in HeLa cells led to saturable 5-HT uptake activity (Km = 858 nM). This 5-HT uptake was blocked by selective 5-HT inhibitors, such as citalopram, litoxetine, sertraline, and indalpine, with Ki values in the low nanomolar range, and it exhibited a pharmacological profile similar to that found in rat brain. [3H]Citalopram binding to membrane preparations of the transfected cells occurred to a single class of high-affinity binding sites (Kd = 5.3 nM) and was potently inhibited by selective 5-HT uptake inhibitors. The pharmacological profile of [3H]citalopram binding to these transfected cells showed a good correlation with that of [3H]paroxetine binding to the rat cerebral cortical 5-HT transporter (r = 0.79). These data confirm that the full pharmacological characteristics of the 5-HT transport system are conferred by the expression of the 630 amino acid human placental 5-HT transporter polypeptide. [3H]Citalopram should, therefore, provide a useful probe for more insights at a molecular level into this cloned 5-HT transport system.
Agnel
M
M
Synthélabo Recherche, Rueil Malmaison, France.
Esnaud
H
H
Langer
S Z
SZ
Graham
D
D
D000929:Antidepressive Agents, Tricyclic / Q000494:pharmacology; D001667:Binding, Competitive; D002352:Carrier Proteins / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D015283:Citalopram / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary; D006367:HeLa Cells; D006801:Humans; D008562:Membrane Glycoproteins / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D011869:Radioligand Assay; D011994:Recombinant Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism; D050486:Serotonin Plasma Membrane Transport Proteins; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology; D014316:Tritium
D000929:Antidepressive Agents, Tricyclic; D002352:Carrier Proteins; D015283:Citalopram; D018076:DNA, Complementary; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D011994:Recombinant Proteins; D012701:Serotonin; D050486:Serotonin Plasma Membrane Transport Proteins; D017367:Selective Serotonin Reuptake Inhibitors; D014316:Tritium; C493230:SLC6A4 protein, human