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Temperature Sensitivity of Agonist High‐Affinity Binding Sites of Solubilized and Reconstituted D 1 Dopamine Receptors
Author(s) -
Sidhu Anita,
Kimura Kazuhiro
Publication year - 1994
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1994.63010201.x
Subject(s) - receptor , agonist , radioligand , chemistry , binding site , radioligand assay , dopamine receptor , ligand (biochemistry) , population , dopamine , biophysics , biochemistry , biology , endocrinology , demography , sociology
Solubilization of rat striatal membranes with sodium cholate, followed by reconstitution into phospholipid vesicles, leads to a 6.5‐fold increase in the agonist high‐affinity binding sites of the D 1 dopamine receptor. These high‐affinity binding sites display differential sensitivity toward temperature. When reconstituted receptors were preincubated for 1 h at 0–4°C (on ice) or at 22°C (room temperature) followed by radioligand binding assays with dopamine, neither the high‐affinity values of the receptor for dopamine nor the percent receptors in the high‐affinity state (31–39%) were changed from control reconstituted receptors, which were not subject to any preincubations. At 30°C, there was a partial loss in the number of high‐affinity D 1 receptors with only 25% of the total receptor population in the high‐affinity state; there was no change in the affinity values of the high‐affinity binding sites. At 37°C, there was a 40% loss in total number of D 1 receptor binding sites. All the high‐affinity binding sites were lost and the remaining 60% of binding activity represented the low‐affinity binding state of the receptor. These results indicate that the high‐affinity binding sites of the reconstituted D 1 dopamine receptors are uniquely sensitive to higher temperatures.