Cloning, expression, functional coupling and pharmacological characterization of the rat dopamine D4 receptor

Abstract

It has been difficult to observe functional coupling of the D4 receptor to second messenger systems and a robust functional assay system for this receptor is still lacking. In the present study, the rat dopamine D4 receptor was cloned from rat retina. Sequence comparison revealed identity with the published sequence of Ashgari and coworkers, including the two amino acid insertions (V-Q) at position 92 which are not present in the published sequence of O'Malley and coworkers. The rat dopamine D4 receptor was stably expressed in Chinese hamster lung fibroblast CCL39 cells. [3H]spiperone saturation binding yielded a B(max) of 2370±546 fmol/mg protein and a pK(D) of 8.74±0.14 (n=4). Forskolin-st..