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Protein / target

Estrogen receptor

Encoded byESR1P03372Homo sapiensSwiss-Prot
Clinically validated
Therapeutic maturity
37
Approved medicines
Open Targets target-level
View by indication →
30
Clinical trials
Small-molecule tractable
Druggability
Approved Drug

Protein at a glance

Biological role

Sequence-specific double-stranded DNA binding

Strongest disease association

Estrogen resistance syndrome

Via encoding gene ESR1 · Genetic evidence · score 0.76

Therapeutic position

Established drug target

Small molecules and protein degraders

Research activity

Emerging research

2 papers · latest 2024

Derived from structured UniProt, Open Targets and literature data on this page.

Protein profile

UniProt 2026_02

Canonical identity and biological annotation from UniProt.

Function overview

Nuclear hormone receptor.

View complete UniProt function annotation

Nuclear hormone receptor. The steroid hormones and their receptors are involved in the regulation of eukaryotic gene expression and affect cellular proliferation and differentiation in target tissues. Ligand-dependent nuclear transactivation involves either direct homodimer binding to a palindromic estrogen response element (ERE) sequence or association with other DNA-binding transcription factors, such as AP-1/c-Jun, c-Fos, ATF-2, Sp1 and Sp3, to mediate ERE-independent signaling. Ligand binding induces a conformational change allowing subsequent or combinatorial association with multiprotein coactivator complexes through LXXLL motifs of their respective components. Mutual transrepression occurs between the estrogen receptor (ER) and NF-kappa-B in a cell-type specific manner. Decreases NF-kappa-B DNA-binding activity and inhibits NF-kappa-B-mediated transcription from the IL6 promoter and displace RELA/p65 and associated coregulators from the promoter. Recruited to the NF-kappa-B response element of the CCL2 and IL8 promoters and can displace CREBBP. Present with NF-kappa-B components RELA/p65 and NFKB1/p50 on ERE sequences. Can also act synergistically with NF-kappa-B to activate transcription involving respective recruitment adjacent response elements; the function involves CREBBP. Can activate the transcriptional activity of TFF1. Also mediates membrane-initiated estrogen signaling involving various kinase cascades. Essential for MTA1-mediated transcriptional regulation of BRCA1 and BCAS3 (PubMed:17922032). Maintains neuronal survival in response to ischemic reperfusion injury when in the presence of circulating estradiol (17-beta-estradiol/E2) (By similarity)

Subcellular location

NucleusCytoplasmCell membraneGolgi apparatus
Domains and Gene Ontology detail (61)

Domains & features

NR LBD

Gene Ontology

  • Cchromatin
  • Ccytoplasm
  • Ccytosol
  • Ceuchromatin
  • CGolgi apparatus
  • Cmembrane
  • Cnucleoplasm
  • Cnucleus
  • Cplasma membrane
  • Cprotein-containing complex
  • F14-3-3 protein binding
  • FATPase binding

595 aa · 66 kDa · 4 isoforms

Biological roles

Reactome v97

What this protein does, drawn together from its UniProt function, Gene Ontology terms and Reactome pathways.

Nuclear receptor signallingGO · ReactomeCell proliferation & survivalReactomeReceptor tyrosine kinase signallingReactomeOncogenic signallingReactomeTranscriptional regulationUniProt · GO · Reactome
View supporting evidence

Nuclear receptor signalling

  • ·nuclear receptor activity
  • ·nuclear receptor-mediated steroid hormone signaling pathway
  • ·steroid hormone receptor signaling pathway
  • ·Nuclear Receptor transcription pathway

Cell proliferation & survival

  • ·PIP3 activates AKT signaling
  • ·PI5P, PP2A and IER3 Regulate PI3K/AKT Signaling

Receptor tyrosine kinase signalling

  • ·Nuclear signaling by ERBB4

Oncogenic signalling

  • ·Constitutive Signaling by Aberrant PI3K in Cancer

Transcriptional regulation

  • ·Nuclear hormone receptor. The steroid hormones and their receptors are involved in the r…
  • ·DNA-binding transcription activator activity, RNA polymerase II-specific
  • ·DNA-binding transcription factor activity
  • ·DNA-binding transcription factor activity, RNA polymerase II-specific
View underlying pathways (17)

Concepts derived from UniProt GO Reactome — each badge above shows which sources supported that role.

Interaction neighbourhood

STRING v12.0

Proteins with the strongest functional or physical association. Node size and line weight reflect STRING confidence; hover or select a partner to inspect one association.

SRCJUNHSP90A…NCOA1IGF1RBRCA1NRIP1NCOA3NCOR1SP1ESR1

10 strongest partners — larger node and heavier line mean higher confidence

Functional and physical associations from STRING v12.0. Only associations with this protein are drawn — partner-to-partner links are not part of this evidence.

Approved medicines with mapped indications

4 medicines · 8 areas

Approved therapies targeting this protein, grouped by what they are approved to treat — the disease-first view of the medicines below. Relationships come from the canonical approved-indication graph (ChEMBL phase-4), the same source as the drug cards.

Atrophy2 medicines
Breast Neoplasms2 medicines
Dyspareunia2 medicines
Hypogonadism1 medicine
Osteoporosis1 medicine
Osteoporosis, Postmenopausal1 medicine
Primary Ovarian Insufficiency1 medicine
Neoplasms2 medicines

37 medicines meet Open Targets' target-level approved-medicine definition; the 4 shown here are those on this page with a canonical approved disease indication in the graph. Approved indications from ChEMBL (phase-4), via the canonical drug→disease graph.

Drugs targeting this protein

8

How approved and investigational drugs engage this protein — mechanism and action type, direct vs complex targeting, and how broadly each acts across other targets. A drug-first view (the section above groups the approved ones disease-first); direct binders with few recorded targets are listed first.

Estradiol
Narrow target profileApprovedAgonist

Estrogen receptor alpha agonist

Indicated for Atrophy, Breast Neoplasms, Dyspareunia, Hypogonadism

Direct interaction with this protein · Only this protein recorded as a target

fulvestrant
Narrow target profileApprovedAntagonist

Estrogen receptor alpha antagonist

Indicated for Breast Neoplasms, Neoplasms

Direct interaction with this protein · Only this protein recorded as a target

Diethylstilbestrol
Narrow target profileApprovedAgonist

Estrogen receptor alpha agonist

Indicated for Neoplasms

Direct interaction with this protein · Only this protein recorded as a target

Estrone
Narrow target profileApprovedAgonist

Estrogen receptor alpha agonist

Direct interaction with this protein · Only this protein recorded as a target

elacestrant
Narrow target profileApprovedDegrader

Estrogen receptor alpha degrader

Direct interaction with this protein · Only this protein recorded as a target

Lasofoxifene
ApprovedModulator

Estrogen receptor modulator

Acts on a complex — shared with ESR2 · 1 of 2 recorded protein targets — narrow recorded profile

View all 8 targeting drugs
Ospemifene
ApprovedModulator

Estrogen receptor modulator

Indicated for Atrophy, Dyspareunia

Acts on a complex — shared with ESR2 · 1 of 2 recorded protein targets — narrow recorded profile

Afimoxifene
Phase 2Modulator

Estrogen receptor modulator

Acts on a complex — shared with ESR2 · 1 of 3 recorded protein targets — narrow recorded profile

ChEMBL mechanism, action type, target identity and approved indications. Open Targets clinical status.

Translational evidence

Open Targets 26

Why this target matters therapeutically, strongest evidence first. Disease associations are gene-level (via the gene that encodes this protein) and open into the full confidence synthesis; the development universe, tractability and safety annotations are target-level, from Open Targets.

Strongest disease associations · via encoding gene ESR1

Gene-level evidence surfaced through the gene ESR1 that encodes this protein — not a direct protein–disease relationship. Ranked by Forefront's causal-directness weighting, so genetically- and clinically-evidenced diseases lead over ones that merely share the literature.

Osteoporosis
0.93Well supported

Clinical evidence dominant · Open Targets 0.71

Endometriosis
0.91Well supported

Clinical evidence dominant · Open Targets 0.67

Breast Neoplasms
0.90Well supported

Clinical evidence dominant · Open Targets 0.66

Neoplasms
0.87Well supported

Clinical evidence dominant · Open Targets 0.66

Estrogen resistance syndrome
0.82Well supported

Genetic evidence dominant · Open Targets 0.66

View evidence synthesis (5)
OsteoporosisWell supported
0.93
agreement 0.841.00
Clinical44%Genetic39%Animal model10%Literature7%

Open Targets aggregate 0.71 · 4 independent evidence families

EndometriosisWell supported
0.91
agreement 0.801.00
Clinical46%Genetic44%Literature9%

Open Targets aggregate 0.67 · 3 independent evidence families

Breast NeoplasmsWell supported
0.90
agreement 0.791.00
Clinical47%Genetic43%Literature10%

Open Targets aggregate 0.66 · 3 independent evidence families

NeoplasmsWell supported
0.87
agreement 0.770.96
Clinical50%Somatic mutation21%Genetic19%Literature11%

Open Targets aggregate 0.66 · 4 independent evidence families

Estrogen resistance syndromeWell supported
0.82
agreement 0.700.94
Genetic76%Animal model23%Literature1%Genetic literaturedup

Open Targets aggregate 0.66 · 3 independent evidence families · 1 not counted as duplicate

The evidence agreement range shows how closely the independent evidence families agree — it is not a statistical confidence interval, and nothing here is fitted to outcome data. Derived from Open Targets evidence types under Forefront weighting; the per-type scores above show the calculation.

Show all associations
Osteoporosis0.71
Endometriosis0.67
Breast Neoplasms0.66
Neoplasms0.66
Estrogen resistance syndrome0.66
Acne Vulgaris0.61
Hypogonadism0.60

Drug development

51 compounds recorded · 37 approved · 13 in clinical development · 1 earlier-stage

Open Targets' development universe — every compound recorded against the target at any stage, not all approved medicines. Distinct from the 8 drugs that target this protein in Forefront's canonical graph (4 with a mapped approved indication, shown above): these count different sets and are not a subset relation.

View all recorded compounds (10)
MESTRANOLApproval
ARZOXIFENEApproval
SYNTHETIC CONJUGATED ESTROGENS, BApproval
GTX-758Phase 2
ESTRIOLApproval
ESTRADIOL ACETATEApproval
CLOMIPHENEApproval
TOREMIFENEApproval
ESTROGENS, ESTERIFIEDApproval
TOREMIFENE CITRATEApproval

Open Targets known-drugs universe. Drug name and highest clinical stage only — the disease relationship is NOT read from this slice (it carries trial-context noise); approved indications come from the canonical graph above.

Tractability

Small moleculesStrong

Approved Drug and Structure with Ligand support this modality.

AntibodiesEmerging

Feasibility evidence (uniprot loc high conf and go cc high conf) — no clinical-stage drug of this modality recorded.

Protein degradersStrong

Advanced Clinical and Literature support this modality.

Other modalitiesStrong

Approved Drug support this modality.

View underlying tractability evidence (14)
SM · Approved DrugSM · Structure with LigandSM · High-Quality LigandSM · High-Quality PocketSM · Druggable FamilyAB · UniProt loc high confAB · GO CC high confAB · UniProt loc med confPR · Advanced ClinicalPR · LiteraturePR · UniProt UbiquitinationPR · Database UbiquitinationPR · Small Molecule BinderOC · Approved Drug

Raw Open Targets tractability assessment buckets, by modality.

Safety-related annotations

azoospermiaClinPGxbone density lossClinPGxmethamphetamine-induced psychosisClinPGxAltered, Larval developmentAOP-WikiN/A, Breast CancerAOP-Wikiless bone mineral lossClinPGxbreast atrophyBrennan et al. (2024)Promotion, ovarian adenomasAOP-WikiIncrease, Endometrial adenocarcinomasAOP-Wikilarger tamoxifen-induced decrease in total cholesterolClinPGxvaginal atrophyBrennan et al. (2024)regulation of steroid biosynthetic processToxCast

Terms indexed against this target in Open Targets' safety data, with their datasource. These are annotations, not causal claims: the direction of effect (whether activation or inhibition is implicated), species and evidence strength are not captured here, so an entry does not mean that modulating this target is known to cause that condition.

Clinical trials

30

Trials of drugs that target this protein — reached indirectly through those drugs, so a trial listed here studies the drug, not the protein. Ranked by active status, then clinical phase and recency, and spread across the targeting drugs.

View all trials (26)

RECRUITING · via elacestrant · NCT07612215

RECRUITING · via Estradiol · NCT07254429

ClinicalTrials.gov via the drug-target graph.

What's happening now

12

Recent therapeutic activity around this target — regulatory actions, clinical trials and safety signals for 4 drugs that target this protein, plus publications where such a drug is a genuine subject. Every item is reached indirectly through the drug, not the protein itself; incidental mentions (a paper that merely measures a drug) and press items are excluded.

  1. Label change2026-08-19

    Label change: ESTRADIOL (ANDA218507)

    fda · regulatory · fda · via Estradiol

  2. Trial status changed2026-08-17

    A Phase Ib/III, Open-label, Randomised Study of Capivasertib Plus CDK4/6 Inhibitors and Fulvestrant Versus CDK4/6 Inhibitors and Fulvestrant in Hormone Receptor-Positive and Human Epidermal Growth Factor Receptor 2-Negative Locally Advanced, Unresectable or Metastatic Breast Cancer (CAPItello-292)

    Status changed to Active, not recruiting · ClinicalTrials.gov · via fulvestrant

  3. Trial status changed2026-08-13

    A Phase 3 Randomized, Open-Label Study of OP-1250 Monotherapy vs Standard of Care for the Treatment of ER+, HER2- Advanced or Metastatic Breast Cancer Following Endocrine and CDK 4/6 Inhibitor Therapy (OPERA-01)

    Status changed to Active, not recruiting · ClinicalTrials.gov · via fulvestrant

  4. Trial status changed2026-08-11

    A Randomized, Open-label, Phase III Study of SIM0270 Combined With Everolimus Versus Treatment of Physician's Choice in Patients With CDK4/6 Inhibitors Previously Treated , ER+/HER2- Locally Advanced or Metastatic Breast Cancer

    Status changed to Active, not recruiting · ClinicalTrials.gov · via fulvestrant

  5. Trial status changed2026-08-04

    An Open-Label, Multicenter, First-in-Human, Phase 1 Study of BBI-940 in Advanced or Metastatic Breast Cancer: Kinesin Oral Molecular Degrader for Oncology (KOMODO-1)

    Status changed to Terminated · ClinicalTrials.gov · via fulvestrant

  6. Label change2026-06-24

    Label change: ELACESTRANT (NDA217639)

    fda · regulatory · fda · via elacestrant

  7. Label change2026-06-08

    Label change: ESTRADIOL (ANDA075182)

    fda · regulatory · fda · via Estradiol

  8. Label change2026-06-08

    Label change: ESTRADIOL (ANDA075182)

    fda · regulatory · fda · via Estradiol

  9. New publication2024-09-10
    Hormonal Treatments and Vaginal Moisturizers for Genitourinary Syndrome of Menopause : A Systematic Review.

    Annals of internal medicine · 2024 · 14 citations · Europe PMC · via Ospemifene

  10. New publication2024-07-04
    TFEB controls syncytiotrophoblast formation and hormone production in placenta.

    Cell death and differentiation · 2024 · 14 citations · Europe PMC · via Estradiol

  11. New publication2024-06-01
    Inhibition of lysine acetyltransferase KAT6 in ER<sup>+</sup>HER2<sup>-</sup> metastatic breast cancer: a phase 1 trial.

    Nature medicine · 2024 · 47 citations · Europe PMC · via fulvestrant

  12. New publication2024-05-14
    Associations of Testosterone and Related Hormones With All-Cause and Cardiovascular Mortality and Incident Cardiovascular Disease in Men : Individual Participant Data Meta-analyses.

    Annals of internal medicine · 2024 · 47 citations · Europe PMC · via Estradiol

Objective event titles are shown unmodified; the event kind and significance line are derived from structured fields. Forefront AttentionEvent stream aggregating Europe PMC Regulatory filings ClinicalTrials.gov.

Research activity

2 papers · to 2024

Papers linked directly to this protein. This is the protein's own literature — descriptor-derived papers are kept separate below.

Most cited

Recent

Europe PMC papers linked directly to this protein.

Related family literature

35

Papers about “Receptors, Estrogen” — a broader family this protein belongs to. Shown as context; not counted as papers specifically about this protein.

Biomarkers of response and resistance to immune checkpoint inhibitors in breast cancer.

Li M · Breast (Edinburgh, Scotland) · 2025

via Receptors, Estrogen

Landscape of Baseline and Acquired Genomic Alterations in Circulating Tumor DNA with Abemaciclib Alone or with Endocrine Therapy in Advanced Breast Cancer.

Goetz MP · Clinical cancer research : an official journal of the American Association for Cancer Research · 2024

via Receptors, Estrogen

Datopotamab Deruxtecan in Advanced or Metastatic HR+/HER2- and Triple-Negative Breast Cancer: Results From the Phase I TROPION-PanTumor01 Study.

Bardia A · Journal of clinical oncology : official journal of the American Society of Clinical Oncology · 2024

via Receptors, Estrogen

Abemaciclib plus a nonsteroidal aromatase inhibitor as initial therapy for HR+, HER2- advanced breast cancer: final overall survival results of MONARCH 3.

Goetz MP · Annals of oncology : official journal of the European Society for Medical Oncology · 2024

via Receptors, Estrogen

Europe PMC literature, reached through curated HGNC family membership. Membership is a taxonomic relationship — it does not imply this protein participates in every mechanism these papers discuss.

Related literature

35

Papers indexed under “Receptors, Estrogen” — a subject heading that covers this protein without being specific to it. Shown as context; not counted as this protein's own research activity.

Biomarkers in breast cancer 2024: an updated consensus statement by the Spanish Society of Medical Oncology and the Spanish Society of Pathology.

Colomer R · Clinical & translational oncology : official publication of the Federation of Spanish Oncology Societies and of the National Cancer Institute of Mexico · 2024

Rat Models of Hormone Receptor-Positive Breast Cancer.

Nicotra R · Journal of mammary gland biology and neoplasia · 2024

Europe PMC literature, reached through a MeSH descriptor linked to this protein.