Dopamine D1A and D1B receptor subtypes belong to the superfamily of G protein-coupled
receptors. Both receptors are coupled to the activation of adenylyl cyclase and exhibit
distinct brain distribution. To identify functional differences, binding and stimulation of
adenylyl cyclase were assessed in 293 cells expressing transiently either dopamine D1A or
D1B receptors. Membranes expressing D1B receptors displayed higher affinities for
agonists than those expressing D1A receptors, whereas antagonist affinities were lower at …