This is one of the five types (D1 to D5) of receptors for dopamine. The activity of this receptor is mediated by G proteins which inhibit adenylyl cyclase. This receptor is expressed in phylogenetically older regions of the brain, suggesting that it plays a role in cognitive and emotional functions. It is a target for drugs which treat schizophrenia, drug addiction, and Parkinson disease. Alternative splicing of this gene results in multiple transcript variants that would encode different isoforms, although some variants may be subject to nonsense-mediated decay (NMD).