Molecular cloning of glucocorticoid and mineralocorticoid receptors in Eurasian Tree Sparrow Passer montanus

Abstract Glucocorticoids mediate various essential biological functions by binding to and activating their specific receptors. In vertebrates, interactions between glucocorticoid receptors (GR) and mineralocorticoid receptors (MR) play an important role in the feedback pathways of glucocorticoid regulation. In free-living birds, a number of studies have demonstrated seasonal regulation of the adrenocortical response to stress, but little is known about their downstream receptors, GR and MR. In this study, we successfully cloned the full-length open reading frames (ORFs) of the GR (eGR) and the MR (eMR) cDNAs from a passerine species, the Eurasian Tree Sparrow Passer montanus. The ORFs eGR contains 2,322 base pairs encoding 773 amino acids, and the eMR contains 2,952 base pairs encoding 983 amino acids. The eGR and eMR are highly conserved in their gene and amino acid sequences and in their secondary and 3D structures when compared with other species of birds and vertebrates.