Estrogen receptors in gastric cancer: Advances and perspectives

Figure 1 Protein structure of estrogen receptors. Two different forms of ER are encoded by two distinct genes located in chromosomes 6 and 14 and produce two proteins with 595 and 530 amino acids in full length, respectively. Six evolutionary conserved domains, namely A-F, are shared by different ERs. For ERα isoforms, compared to the full length ERα66, ERα46 lacks AF-1 domain (A/M), ERα36 lacks AF-1 and partial AF-2 domains but is equipped an extra different C-terminal. For alternatively-spliced ERβ isoforms, they differ mainly at their C-terminals. AF-1: Transcriptional activation factor-1; DBD: DNA-binding domain; NLS: Nuclear localization signals; LBD: Ligand binding domain; ERs: Estrogen receptors; AA: Amino acid.