Estrogen receptor alpha (ER-alpha) and Estrogen receptor beta (ER-beta) (ER-alpha/beta)

Estrogen receptor alpha (ER-alpha) and Estrogen receptor beta (ER-beta) are ligand-activated transcription factors belonging to the nuclear receptor superfamily that play pivotal roles in growth, development, and homeostasis (UniProt: P03372, Q92731). These receptors share a conserved structure featuring a C-terminal ligand-binding domain (LBD), which is the primary target for endogenous estrogens and therapeutic drugs. Upon ligand binding, the LBD undergoes a conformational shift that facilitates receptor dimerization and translocation to the nucleus, where the complex binds to specific DNA sequences to regulate gene transcription (StatPearls: NBK538260). ER-alpha is predominantly associated with the proliferative effects of estrogen in the breast and uterus, making it a central target in the treatment of hormone-receptor-positive breast cancer. In contrast, ER-beta often exhibits anti-proliferative properties and is expressed in a wider range of tissues, including the lungs and central nervous system (PubMed: PMC10141435). Pharmacological agents targeting the LBD include agonists for hormone replacement therapy, antagonists for oncology, and selective estrogen receptor modulators (SERMs) that provide tissue-specific estrogenic or anti-estrogenic effects. Recent therapeutic advances focus on selective estrogen receptor degraders (SERDs) that bind the LBD to induce receptor proteolysis, addressing resistance mechanisms in advanced cancers (PubMed: PMC7465043).

Other names

ESR1ESR2NR3A1NR3A2ER-alphaER-betaEstradiol receptorNuclear receptor subfamily 3 group A member 1/2Ligand-binding domain (LBD)

Drugs bind to the ligand-binding domain (LBD), inducing conformational changes (specifically in helix 12) that either promote (agonism) or block (antagonism) the recruitment of co-activator proteins, thereby modulating the transcription of target genes (PubMed: PMC10141435). SERMs induce tissue-specific conformations, while SERDs trigger receptor degradation (PubMed: PMC7465043).