| Popis: |
Publisher Summary In this chapter a comparative approach of the dopamine 1 (D1)-receptor class has been undertaken to analyze in detail the dopamine-receptor multiplicity of D1-like receptors in vertebrates by cloning the corresponding genes in most of the main groups of vertebrates. The aim of the chapter is to identify the events that led to the emergence of a “new” D1-receptor gene in the evolution of vertebrates. This phylogenetical approach provides conclusive evidence for the existence of two other subtypes of D1 receptors, one named D1C, found in all the jawed vertebrates except mammals, and one subtype termed D1D, only to be found in birds. Therefore, the D1-receptor class comprises three to four subtypes in “higher” vertebrates, virtually indentical to other catecholamine receptor families, indicating that the gene duplications at the origin of this receptor multiplicity occurred before or concomitantly with the appearance of Chondrychtians (cartilaginous fish). As all of the known bioamine receptor subtypes are expressed in the central nervous system, it is proposed that the bioamine and dopamine D1-receptor diversification accompanies in some respect the genetic mechanisms leading to the encephalization of the vertebrate nervous system. Acquisition and changes in the expression pattern of bioamine receptors is likely to have been the major factor of duplicated gene conservation in vertebrates. |
