COUP-TFs

Chicken ovalbumin upstream promoter transcription factors (COUP-TFs) are orphan NR transcription factors belonging to subfamily 2 group F of the NR (NR2F) family. From the N-terminus to the C-terminus, all NR2F proteins have six domains: 1) an A/B domain, which contains the activating function-1 (AF-1) domain; 2) the C domain, which contains the DNA-binding domain (DBD); 3) the D domain (a linker); 4) the E domain, which is comprised of the ligand-binding domain (LBD) and 5) an AF-2 domain; 6) the F domain (C-terminal). In vertebrates, three homologous subtypes have been identified: COUP-TFI (EAR-3, NR2F1), COUP-TFII (ARP-1, NR2F2) and COUP-TFIII (EAR-2, NR2F6). COUP-TFI and COUP-TFII may activate or repress the transcription of genes, but COUP-TFIII primarily acts to repress transcription. Significantly, COUP-TFs are known for their cell-fate-determining functions in the heart, veins, eye, brain, and reproductive system.