Schematic structure COUP-TFII and known mechanism of its transcriptional regulation. A) Schematic structure of human COUP-TFII proteins. DNA-binding domain (DBD); ligand-binding domain (LBD) B) COUP-TFII binds to 5′-AGGTCA-3′ motif palindromes (DR site), either directly (homodimer) or indirectly, through heterodimer formation with other proteins (e.g. RXRs) to regulate downstream target gene expression. In addition, COUP-TFII can also bind to Sp1 sites through interaction with Sp1 to cooperatively activate gene expression.