- Early emergence of three dopamine D1 receptor subtypes in vertebrates. Molecular phylogenetic, pharmacological, and functional criteria defining D1A, D1B, and D1C receptors in European eel Anguilla anguilla. Cardinaud, B., Sugamori, K.S., Coudouel, S., Vincent, J.D., Niznik, H.B., Vernier, P. J. Biol. Chem. (1997)