The D1 subtype is the most abundant dopamine receptor in the central nervous system. This G protein coupled receptor stimulates adenylyl cyclase and activates cyclic AMP dependent protein kinases. D1 receptors regulate neuronal growth and development, mediate some behavioral responses, and modulate dopamine receptor D2 mediated events. Alternate transcription initiation sites result in two transcript variants of this gene. Dopamine receptor D1 has been reported mostly in various regions of the brain. ESTs have been isolated from normal olfactory epithelium and cancerous genitourinary tract libraries.