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Titolo:
MECHANISTIC ANALYSES OF ION DEPENDENCES IN A HIGH-AFFIINITY HUMAN SEROTONIN TRANSPORT-SYSTEM IN TRANSFECTED MURINE FIBROBLAST CELLS
Autore:
CHANG AS; LAM DMK;
Indirizzi:
BAYLOR COLL MED,CTR BIOTECHNOL,4000 RES FOREST DR THE WOODLANDS TX 77381
Titolo Testata:
Journal of physiology
fascicolo: 3, volume: 510, anno: 1998,
pagine: 903 - 913
SICI:
0022-3751(1998)510:3<903:MAOIDI>2.0.ZU;2-J
Fonte:
ISI
Lingua:
ENG
Soggetto:
PLASMA-MEMBRANE VESICLES; NEUROTRANSMITTER TRANSPORTERS; PLATELET 5-HYDROXYTRYPTAMINE; )H-3>IMIPRAMINE BINDING; RECEPTOR SUBTYPES; BLOOD PLATELETS; RAT-BRAIN; CHLORIDE; EXPRESSION; GRADIENTS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
41
Recensione:
Indirizzi per estratti:
Citazione:
A.S. Chang e D.M.K. Lam, "MECHANISTIC ANALYSES OF ION DEPENDENCES IN A HIGH-AFFIINITY HUMAN SEROTONIN TRANSPORT-SYSTEM IN TRANSFECTED MURINE FIBROBLAST CELLS", Journal of physiology, 510(3), 1998, pp. 903-913

Abstract

1. A clonal cell line, L-S1, has been identified from transfection ofhuman genomic DNA into cultured mouse L-M fibroblasts. Because this transfectant cell line stably expresses a high-affinity serotonin (5-HT) transport mechanism with kinetic and pharmacological properties comparable to those of other serotonin uptake systems, it was used to investigate the mechanistic involvement of Na+ and Cl- ions in the ligand binding and kinetic uptake processes of this system. 2. Intact transfectant cells, when incubated at low temperature (4 degrees C), enabled quantitative assessment of imipramine-displaceable 5-[H-3]HT binding to the 5-HT transport system. This binding activity is insensitive to the presence of various ligands specific for 5-HT receptor subtypes. 3. Imipramine-displaceable 5-[H-3]HT binding to intact L-S1 cells was shown to be a Cl--dependent but Na+-independent process. Chloride ions lack binding co-operativity in facilitating ligand binding. Changes in external Cl- concentration altered the K-d but not the B-max of binding. 4. The overall transport activity was observed to be highly dependent on both external Na+ and Cl- concentrations, characterized by a 5-HT:Na+:Cl- coupling ratio of 1 : 1 : 1 per transport cycle. Alterationsin the external concentrations of both Na+ and Cl- ions altered only the K-m and not the V-max of transport. 5. Both binding and kinetic results are consistent with kinetic modelling predictions of the Cl- ionin facilitating 5-HT binding to the transport system, and of the Na+ ion in enabling translocation of bound 5-HT across the plasma membrane. Thus, Na+ and Cl- ions facilitate mechanistically distinct and discernible functions in the transport cycle.

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Documento generato il 22/01/20 alle ore 12:39:27