Figure 1.

Schematic structure and sequence organization of ERα and ERβ. They differ in terms of amino acid numbers. ERα consists of 595 amino acids, while ERβ contains 530 amino acids. ERα and ERβ share identical characteristics. They are formed by different domains. Amino-terminal A/B domains share 18% amino-acid homology between the ERs. C region (97%) consists of DNA-binding domain. D domain (30%) contains a nuclear localization signal. Multifunctional carboxyl-terminal (E) domain, which shows 59% amino-acid identity between the ERs. The carboxyl-terminal F domain shares an 18% amino-acid identity. (DBD: DNA-binding domain; LBD: ligand-binding domain; AF-1: activation domain).