D(2) dopamine receptor (dopamine D2 receptor) 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. Genetic variations in the dopamine D2 receptor are implicated in the genetic susceptibility to alcoholism. Genetic variations in the dopamine D2 receptor are a protective factor against the development of withdrawal symptoms but might also be a risk factor in a highly burdened subgroup of alcoholics with a paternal and grandpaternal history of alcoholism and might contribute to suicide risk in alcoholics.