Fig. 5.

Primary Structure of ERα, ERβ, and GPR30. Similar to other members of the nuclear receptor superfamily, ERα and ERβ share a common structure with five functional domains termed A/B, C, D, E and F. Domain A/B contains the activation function-1 1 (AF-1). Domain C is the DNA binding domain. Domain D is the hinge domain, linking domain C and E. The ligand binding cavity and activation function 2 (AF-2) are located in domain E. Domain F includes co-factor recruitment regions. GPR30 is a G-coupled protein receptor that has estrogenic activity and shares little homology with the classical ERs. GPR30 consists of an N-terminal domain, a 7- transmembrane domain and a C-terminal domain.