Dopamine D2 receptors internalize in their low-affinity state.
The present study was done in order to determine whether dopamine internalizes D2 receptors in CHO cells and whether the high-affinity or the low-affinity state of the dopamine D2 receptor is associated with dopamine-induced internalization of dopamine D2 receptors. Using [3H]sulpiride to label D2Long receptors in CHO cells, it was found that dopamine lowered the binding of [3H]sulpiride by 20%. Although the high-affinity states of D2 were converted to low-affinity states by guanine nucleotide, the latter had no effect in blocking the dopamine-induced reduction in [3H]sulpiride binding, indicating that the dopamine-induced internalization of D2 receptors occurred with D2 in the low-affinity state.
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Department of Pharmacology, Medical Science Building, Room 4344, University of Toronto, Toronto, Ont. M5S 1A8.
Seeman
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Kapur
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D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects / Q000502:physiology; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D016466:CHO Cells; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D003208:Concanavalin A / Q000494:pharmacology; D006224:Cricetinae; D004298:Dopamine / Q000378:metabolism* / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology*; D006150:Guanine Nucleotides / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology*; D020891:Raclopride / Q000494:pharmacology; D011869:Radioligand Assay; D017448:Receptors, Dopamine D2 / Q000187:drug effects / Q000378:metabolism*; D013395:Sucrose / Q000494:pharmacology; D013469:Sulpiride / Q000494:pharmacology
D018492:Dopamine Antagonists; D006150:Guanine Nucleotides; D017448:Receptors, Dopamine D2; D003208:Concanavalin A; D020891:Raclopride; D013395:Sucrose; D013469:Sulpiride; D004298:Dopamine