Dopamine D3 Receptor Antagonists: ProductsDRD3 is the D3 subtype of the five (D1-D5) dopamine receptors. The activity of the D3 subtype receptor is mediated by G proteins which inhibit adenylyl cyclase. It is localized to the limbic areas of the brain, which are associated with cognitive, emotional, and endocrine functions. Genetic variations may be associated with susceptibility to hereditary essential tremor 1. Alternative splicing results in transcript variants encoding different isoforms. This variant represents the predominant transcript and encodes the longer isoform (a).