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 iso