Conformation of dopamine at the dopamine receptor.
Tritiated dopamine was used to label the dopamine receptor in membranes isolated from the rat corpus striatum. Scatchard analysis of displacement of [3H]dopamine by nonradioactive dopamine indicated the presence of two binding sites. The similarities in affinity, capacity, and drug specificity of the high-affinity site in the striatal membranes from rat and the binding site in the membranes from the calf caudate nucleus suggest that [3H]dopamine labels the same site in both species. In order to determine what conformation of dopamine is preferred at the dopamine receptor site, conformationally restricted analogs of dopamine--namely, the cis and trans 2-amino-1(3,4-dihydroxyphenyl)cyclobutane hydrochlorides--were tested for their affinity to the receptor. Compared to the cis conformation, the trans-restricted analogs had more affinity for the receptor site, indicating that dopamine probably interacts with the receptor in the trans conformation.
D000818:Animals; D003342:Corpus Striatum / Q000378:metabolism; D004298:Dopamine / Q000031:analogs & derivatives / Q000378:metabolism; D007536:Isomerism; D007700:Kinetics; D008968:Molecular Conformation; D051381:Rats; D011954:Receptors, Dopamine / Q000378:metabolism*; D013329:Structure-Activity Relationship
D011954:Receptors, Dopamine; D004298:Dopamine