Molecular biology of the invertebrate dopamine receptors

Dopamine is found in the nervous systems of both vertebrates and invertebrates. However, the specific actions of dopamine depend on the dopamine receptor type that is expressed in the target cell. As in mammals, different subtypes of dopamine receptors have been cloned and characterized from invertebrates, and these receptor subtypes have different structural and functional properties. Understanding how these receptors respond to dopamine and in which cells each receptor type is expressed is key to our understanding of the role of dopamine signaling. Comparison of the amino acid sequences and experimentally determined functional properties suggest that there are at least three distinct types of dopamine receptors in invertebrates. This review focuses on invertebrate dopamine receptors for which the genes have been isolated and identified, and examines our current knowledge of the functional and structural properties of these receptors, and their pharmacology and expression.