Submitted on November 22, 2006
Accepted on October 10, 2007
Characterization and functional divergence of the 
1-adrenoceptor gene family: insights from rainbow trout (Oncorhynchus mykiss)
Xi Chen1, Steven F Perry1, Stephane Aris-Brosou1, Corrado Selva1, and Thomas W Moon2*
1 Biology, University of Ottawa, Ottawa, Canada
2 Biology, University of Ottawa, ottawa, Canada
* To whom correspondence should be addressed. E-mail: tmoon{at}uottawa.ca.
Currently three 
1-adrenoceptor (AR) types are recognized in vertebrates: 1A-, 1B- and 1D-ARs. These 1-subtypes have distinct pharmacology and molecular profiles, play crucial roles in metabolic and vascular control, and are the targets for numerous pharmaceuticals, especially those affecting blood pressure and vascular resistance. To better understand the functional divergence within the 1-AR gene family, we sequenced these 1-AR paralogs in the rainbow trout and performed an extensive phylogenetic analysis. We show that these AR genes evolved by duplication events just before the origin of the jawed vertebrates. Our computational analyses suggest that the differences between the three 1-AR subtypes may affect their tissue specificity, ligand specificity and possibly signal transduction processes and desensitization. We also show that, within each subtype, differences exist between fish and mammalian receptors both at the transcriptional and physiological level. These differences however suggest that the role of 1-ARs in fish is more complex than previously thought. Our integrated analysis of the 1-AR gene family suggests that these receptors evolved these distinct features very early within vertebrates.
