Temperature sensitivity of agonist high-affinity binding sites of solubilized and reconstituted D1 dopamine receptors.
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 D1 dopamine receptor. These high-affinity binding sites display differential sensitivity toward temperature. When reconstituted receptors were preincubated for 1 h at 0-4 degrees C (on ice) or at 22 degrees 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 degrees C, there was a partial loss in the number of high-affinity D1 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 degrees C, there was a 40% loss in total number of D1 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 D1 dopamine receptors are uniquely sensitive to higher temperatures.
Sidhu
A
A
Department of Pediatrics, Georgetown University Children's Medical Center, Georgetown University, Washington, D.C.
Kimura
K
K
D000818:Animals; D001665:Binding Sites; D003342:Corpus Striatum / Q000737:chemistry / Q000648:ultrastructure; D004298:Dopamine / Q000378:metabolism; D008297:Male; D011869:Radioligand Assay; D051381:Rats; D017207:Rats, Sprague-Dawley; D017447:Receptors, Dopamine D1 / Q000032:analysis / Q000378:metabolism*; D013696:Temperature
D017447:Receptors, Dopamine D1; D004298:Dopamine