Despite the fact that the human, mouse and rat CBG genes have been cloned, no regulatory studies to identify possible cis-acting sequence elements involved in GC-mediated regulation of CBG have been done. However, DNase I foot-printing of the rat Cbg proximal promoter, has identified five protein binding sites within 2236 bp from the transcription start site in rat liver nuclear extract. These five protein-binding sites are also highly Triclabendazole conserved in the human and mouse Cbg gene. Although the molecular mechanism by which GCs influence CBG levels is unclear, the Cbg promoter has been shown to be transcriptionally regulated via the GR. However, while the Cbg promoter is modulated by GCs, no glucocorticoid response elements seem to be present in the mouse, rat or human CBG gene proximal promoters, suggesting Amoxapine tethering of the GR to other transcription factors rather than binding directly to DNA. Footprints P3�CP5 in the Cbg promoter resemble recognition sequences for DBP, HNF3a and C/EBPb or NF-IL6, and, although binding of these transcription factors has not been confirmed, it is interesting to note that HNF3a and C/EBPb have been reported to be important in GR-mediated signaling. Specifically, protein-protein interaction of the GR with C/EBPb has been reported and both C/EBPb and HNF3a are considered pioneer transcription factors as they increase chromatin accessibility at GC-responsive genes, thereby facilitating GR interaction with GC-responsive promoters. In this study, the molecular mechanism of action of GCmediated repression of CBG expression was investigated. Because no consensus GR binding sites have been identified within the CBG gene promoter, delineation of GR responsiveness within the proximal rat CBG gene promoter was performed. CBG has been extensively characterized as a carrier protein and as a reservoir of endogenous GCs. Because CBG levels directly affect GC bioavailability and consequently GC signaling in homeostatic stress responses, evaluation of factors that modulate CBG levels are of interest. The current study focused on the molecular mechanism of GCmediated inhibition of CBG expression.