Protein / target

Poly [ADP-ribose] polymerase 1

PARP1P09874Homo sapiensSwiss-Prot
Clinically validated
Therapeutic maturity
9
Approved medicines
30
Clinical trials
Small-molecule tractable
Druggability
Approved Drug

Protein at a glance

Biological role

NAD+-histone H2BE35 glutamate ADP-ribosyltransferase activity

Primary system

Nervous system

Strongest disease association

ovarian cancer

Clinical evidence · score 0.62

Therapeutic maturity

Clinically validated target

9 approved medicines against this target

Druggability

Small molecule

Open Targets tractability · Approved Drug

Clinical development

9 approved · 4 in clinical development

30 linked trials

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

Poly-ADP-ribosyltransferase that mediates poly-ADP-ribosylation of proteins and plays a key role in DNA repair (PubMed:17177976, PubMed:18055453, PubMed:18172500, PubMed:19344625, PubMed:19661379, PubMed:20388712, PubMed:21680843, PubMed:22582261, PubMed:23230272, PubMed:25043379, PubMed:26344098, PubMed:26626479, PubMed:26626480, PubMed:30104678, PubMed:31796734, PubMed:32028527, PubMed:32241924, PubMed:32358582, PubMed:33186521, PubMed:34465625, PubMed:34737271). Mediates glutamate, aspartate, serine, histidine or tyrosine ADP-ribosylation of proteins: the ADP-D-ribosyl group of NAD(+) is transferred to the acceptor carboxyl group of target residues and further ADP-ribosyl groups are transferred to the 2'-position of the terminal adenosine moiety, building up a polymer with an average chain length of 20-30 units (PubMed:19764761, PubMed:25043379, PubMed:28190768, PubMed:29954836, PubMed:35393539, PubMed:7852410, PubMed:9315851). Serine ADP-ribosylation of proteins constitutes the primary form of ADP-ribosylation of proteins in response to DNA damage (PubMed:33186521, PubMed:34874266). Specificity for the different amino acids is conferred by interacting factors, such as HPF1 and NMNAT1 (PubMed:28190768, PubMed:29954836, PubMed:32028527, PubMed:33186521, PubMed:33589610, PubMed:34625544, PubMed:34874266). Following interaction with HPF1, catalyzes serine ADP-ribosylation of target proteins; HPF1 confers serine specificity by completing the PARP1 active site (PubMed:28190768, PubMed:29954836, PubMed:32028527, PubMed:33186521, PubMed:33589610, PubMed:34625544, PubMed:34874266). Also catalyzes tyrosine ADP-ribosylation of target proteins following interaction with HPF1 (PubMed:29954836, PubMed:30257210). Following interaction with NMNAT1, catalyzes glutamate and aspartate ADP-ribosylation of target proteins; NMNAT1 confers glutamate and aspartate specificity (By similarity). PARP1 initiates the repair of DNA breaks: recognizes and binds DNA breaks within chromatin and recruits HPF1, licensing serine ADP-ribosylation of target proteins, such as histones (H2BS6ADPr and H3S10ADPr), thereby promoting decompaction of chromatin and the recruitment of repair factors leading to the reparation of DNA strand breaks (PubMed:17177976, PubMed:18172500, PubMed:19344625, PubMed:19661379, PubMed:23230272, PubMed:27067600, PubMed:34465625, PubMed:34874266). HPF1 initiates serine ADP-ribosylation but restricts the polymerase activity of PARP1 in order to limit the length of poly-ADP-ribose chains (PubMed:33683197, PubMed:34732825, PubMed:34795260). In addition to base excision repair (BER) pathway, also involved in double-strand breaks (DSBs) repair: together with TIMELESS, accumulates at DNA damage sites and promotes homologous recombination repair by mediating poly-ADP-ribosylation (PubMed:26344098, PubMed:30356214). Mediates the poly-ADP-ribosylation of a number of proteins, including itself, APLF, CHFR, RPA1 and NFAT5 (PubMed:17396150, PubMed:19764761, PubMed:24906880, PubMed:34049076). In addition to proteins, also able to ADP-ribosylate DNA: catalyzes ADP-ribosylation of DNA strand break termini containing terminal phosphates and a 2'-OH group in single- and double-stranded DNA, respectively (PubMed:27471034). Required for PARP9 and DTX3L recruitment to DNA damage sites (PubMed:23230272). PARP1-dependent PARP9-DTX3L-mediated ubiquitination promotes the rapid and specific recruitment of 53BP1/TP53BP1, UIMC1/RAP80, and BRCA1 to DNA damage sites (PubMed:23230272). PARP1-mediated DNA repair in neurons plays a role in sleep: senses DNA damage in neurons and promotes sleep, facilitating efficient DNA repair (By similarity). In addition to DNA repair, also involved in other processes, such as transcription regulation, programmed cell death, membrane repair, adipogenesis and innate immunity (PubMed:15607977, PubMed:17177976, PubMed:19344625, PubMed:27256882, PubMed:32315358, PubMed:32844745, PubMed:35124853, PubMed:35393539, PubMed:35460603). Acts as a repressor of transcription: binds to nucleosomes and modulates chromatin structure in a manner similar to histone H1, thereby altering RNA polymerase II (PubMed:15607977, PubMed:22464733). Acts both as a positive and negative regulator of transcription elongation, depending on the context (PubMed:27256882, PubMed:35393539). Acts as a positive regulator of transcription elongation by mediating poly-ADP-ribosylation of NELFE, preventing RNA-binding activity of NELFE and relieving transcription pausing (PubMed:27256882). Acts as a negative regulator of transcription elongation in response to DNA damage by catalyzing poly-ADP-ribosylation of CCNT1, disrupting the phase separation activity of CCNT1 and subsequent activation of CDK9 (PubMed:35393539). Involved in replication fork progression following interaction with CARM1: mediates poly-ADP-ribosylation at replication forks, slowing fork progression (PubMed:33412112). Poly-ADP-ribose chains generated by PARP1 also play a role in poly-ADP-ribose-dependent cell death, a process named parthanatos (By similarity). Also acts as a negative regulator of the cGAS-STING pathway (PubMed:32315358, PubMed:32844745, PubMed:35460603). Acts by mediating poly-ADP-ribosylation of CGAS: PARP1 translocates into the cytosol following phosphorylation by PRKDC and catalyzes poly-ADP-ribosylation and inactivation of CGAS (PubMed:35460603). Acts as a negative regulator of adipogenesis: catalyzes poly-ADP-ribosylation of histone H2B on 'Glu-35' (H2BE35ADPr) following interaction with NMNAT1, inhibiting phosphorylation of H2B at 'Ser-36' (H2BS36ph), thereby blocking expression of pro-adipogenetic genes (By similarity). Involved in the synthesis of ATP in the nucleus, together with NMNAT1, PARG and NUDT5 (PubMed:27257257). Nuclear ATP generation is required for extensive chromatin remodeling events that are energy-consuming (PubMed:27257257). Plays a role in sister chromatid cohesion by mediating ADP-ribosylation of RSMC during S phase which promotes the interaction between RSMC and CDCA5/sororin, leading to enhanced interaction of CDCA5/sororin with the cohesin complex and promotion of sister chromatid cohesion (PubMed:41261216)

Subcellular location

ChromosomeNucleusNucleus, nucleolusCytoplasm, cytosolCytoplasm
Domains and Gene Ontology detail (111)

Domains & features

PADR1 zinc-bindingBRCTWGRPARP alpha-helicalPARP catalytic

Gene Ontology

  • Cchromatin
  • Cchromosome, telomeric region
  • Ccytosol
  • Cfibrillar center
  • Cmembrane
  • Cmitochondrion
  • Cnuclear body
  • Cnuclear envelope
  • Cnuclear replication fork
  • Cnucleolus
  • Cnucleoplasm
  • Cnucleus

1014 aa · 113 kDa

Biological roles

Reactome v97

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

Transcriptional regulationUniProt · GO · ReactomeImmune signallingUniProt · GOKinase signallingUniProt · GOApoptosis & cell deathUniProt · GOMetabolic enzyme activityGO
View supporting evidence

Transcriptional regulation

  • ·Poly-ADP-ribosyltransferase that mediates poly-ADP-ribosylation of proteins and plays a…
  • ·transcription regulator complex
  • ·RNA polymerase II-specific DNA-binding transcription factor binding
  • ·transcription regulator activator activity

Immune signalling

  • ·Poly-ADP-ribosyltransferase that mediates poly-ADP-ribosylation of proteins and plays a…
  • ·innate immune response
  • ·negative regulation of innate immune response

Kinase signalling

  • ·Poly-ADP-ribosyltransferase that mediates poly-ADP-ribosylation of proteins and plays a…
  • ·protein kinase binding

Apoptosis & cell death

  • ·Poly-ADP-ribosyltransferase that mediates poly-ADP-ribosylation of proteins and plays a…
  • ·apoptotic process

Metabolic enzyme activity

  • ·NAD DNA ADP-ribosyltransferase activity
  • ·NAD+ poly-ADP-ribosyltransferase activity
  • ·NAD+-histone H2BE35 glutamate ADP-ribosyltransferase activity
  • ·NAD+-histone H2BS6 serine ADP-ribosyltransferase activity
View underlying pathways (8)

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.

CASP3XRCC1XRCC6POLBSMARCA4XRCC5CASP7PRKDCPARGCASP9PARP1

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.

Drugs targeting this protein

4

Whether each drug engages this protein directly or through a complex, and how many other targets are recorded for it. Direct binders with few recorded targets are listed first.

talazoparib
Narrow target profileApprovedInhibitor

Poly [ADP-ribose] polymerase-1 inhibitor

Appears in clinical studies involving breast cancer, neoplasm, psoriatic arthritis, prostate cancer

Direct interaction with this protein · 1 of 2 recorded protein targets — narrow recorded profile

niraparib
Narrow target profileApprovedInhibitor

Poly [ADP-ribose] polymerase-1 inhibitor

Appears in clinical studies involving fallopian tube neoplasm, peritoneal neoplasm, ovarian neoplasm, neoplasm

Direct interaction with this protein · 1 of 2 recorded protein targets — narrow recorded profile

olaparib
ApprovedInhibitor

PARP 1, 2 and 3 inhibitor

Appears in clinical studies involving ovarian cancer, ovarian carcinoma, pancreatic neoplasm, prostate carcinoma

Acts on a complex — shared with PARP3, PARP2 · 1 of 3 recorded protein targets — narrow recorded profile

rucaparib
ApprovedInhibitor

PARP 1, 2 and 3 inhibitor

Appears in clinical studies involving ovarian cancer, neoplasm, fallopian tube cancer, primary peritoneal carcinoma

Acts on a complex — shared with PARP3, PARP2 · 1 of 3 recorded protein targets — narrow recorded profile

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

Translational evidence

Open Targets 26

Why this target matters therapeutically — disease associations, drugs in development, tractability and safety, from Open Targets.

Highest-confidence therapeutic associations

Diseases where a drug acting on this target has already reached clinical development.

ovarian cancer0.97

Clinical · overall 0.62

neoplasm0.92

Clinical · overall 0.59

fallopian tube cancer0.91

Clinical · overall 0.56

breast cancer0.90

Clinical · overall 0.58

ovarian carcinoma0.89

Clinical · overall 0.57

Highest overall evidence

Remaining associations by Open Targets' aggregated evidence score.

prostate cancer0.54

Clinical

primary peritoneal carcinoma0.52

Clinical

breast neoplasm0.51

Clinical

ovarian neoplasm0.51

Clinical

peritoneum cancer0.50

Clinical

Show all associations
ovarian cancer0.62
neoplasm0.59
breast cancer0.58
ovarian carcinoma0.57
fallopian tube cancer0.56
prostate cancer0.54
primary peritoneal carcinoma0.52
breast neoplasm0.51
ovarian neoplasm0.51
peritoneum cancer0.50

Open Targets ranks 1,257 associations for this target and we store the top 10 by aggregated score. The long tail is largely literature co-mention and RNA-expression evidence, not evidence that this target drives those diseases.

Known drugs · 13 total

TALAZOPARIBApproval

breast cancer · neoplasm · psoriatic arthritis

2X-121Phase 2

ovarian cancer · breast cancer · colorectal cancer

AMELPARIB DIHYDROCHLORIDE DIHYDRATEPhase 2

ischemic stroke

VELIPARIBApproval

neoplasm · breast cancer · malignant epithelial tumor of ovary

E-7016Phase 2

melanoma · glioma

NIRAPARIBApproval

fallopian tube neoplasm · peritoneal neoplasm · ovarian neoplasm

SENAPARIBPhase 3

primary peritoneal carcinoma · fallopian tube cancer · ovarian cancer

RUCAPARIBApproval

ovarian cancer · neoplasm · fallopian tube cancer

NIRAPARIB TOSYLATE MONOHYDRATEApproval

ovarian cancer · fallopian tube cancer · peritoneum cancer

RUCAPARIB CAMSYLATEApproval

ovarian cancer · ovarian neoplasm · ovarian carcinoma

Tractability

SM · Approved DrugSM · Structure with LigandSM · High-Quality LigandSM · High-Quality PocketSM · Druggable FamilyPR · LiteraturePR · UniProt UbiquitinationPR · Database UbiquitinationPR · Half-life DataPR · Small Molecule Binder

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.

Show remaining trials (24)

ACTIVE_NOT_RECRUITING · via rucaparib · NCT04624178

ClinicalTrials.gov via the drug-target graph.

Forefront confidence

Synthesis

Our own weighting of the evidence behind each disease association. Human genetics and clinical evidence count for most; literature co-mention counts for little, because two entities sharing an abstract is not evidence that one drives the other.

ovarian cancerWell supported
0.77
agreement 0.610.92
Clinical84%Literature16%

Open Targets aggregate 0.62 · 2 independent evidence families

neoplasmModerately supported
0.73
agreement 0.580.89
Clinical82%Literature18%

Open Targets aggregate 0.59 · 2 independent evidence families

breast cancerModerately supported
0.72
agreement 0.570.88
Clinical82%Literature18%

Open Targets aggregate 0.58 · 2 independent evidence families

ovarian carcinomaModerately supported
0.72
agreement 0.560.87
Clinical82%Literature18%

Open Targets aggregate 0.57 · 2 independent evidence families

fallopian tube cancerModerately supported
0.69
agreement 0.530.84
Clinical99%Literature1%

Open Targets aggregate 0.56 · 2 independent evidence families

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 underlying per-type scores are shown above so the calculation can be checked.

What's happening now

26

Recent activity around this target, drawn from one canonical event stream. Every item is reached through 4 drugs that target this protein, so each event is news about that drug rather than about the protein directly.

  1. Trial results posted2026-07-17

    Phase II Study of Rucaparib and Nivolumab in Patients With Leiomyosarcoma

    Results posted · ClinicalTrials.gov · via rucaparib

  2. Trial status changed2026-07-16

    A Pharmacodynamics-Driven Trial of Talazoparib, an Oral PARP Inhibitor, in Patients With Advanced Solid Tumors and Aberrations in Genes Involved in DNA Damage Response

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

  3. New publication2025-10-07
    Niraparib and abiraterone acetate plus prednisone for HRR-deficient metastatic castration-sensitive prostate cancer: a randomized phase 3 trial.

    Nature medicine · 2025 · 19 citations · Europe PMC · via niraparib

  4. New publication2025-01-31
    Results of a phase Ib study of olaparib with concomitant radiotherapy in soft-tissue sarcoma: a French sarcoma group study.

    Annals of oncology : official journal of the European Society for Medical Oncology · 2025 · 4 citations · Europe PMC · via olaparib

  5. New publication2023-12-04
    First-line talazoparib with enzalutamide in HRR-deficient metastatic castration-resistant prostate cancer: the phase 3 TALAPRO-2 trial.

    Nature medicine · 2024 · 105 citations · Europe PMC · via talazoparib

  6. New publication2023-11-14
    Olaparib for the Treatment of Patients With Metastatic Castration-Resistant Prostate Cancer and Alterations in <i>BRCA1</i> and/or <i>BRCA2</i> in the PROfound Trial.

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology · 2024 · 76 citations · Europe PMC · via olaparib

  7. New publication2023-10-21
    Durvalumab Plus Carboplatin/Paclitaxel Followed by Maintenance Durvalumab With or Without Olaparib as First-Line Treatment for Advanced Endometrial Cancer: The Phase III DUO-E Trial.

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology · 2024 · 259 citations · Europe PMC · via olaparib

  8. New publication2023-02-16
    Rucaparib or Physician's Choice in Metastatic Prostate Cancer.

    The New England journal of medicine · 2023 · 332 citations · Europe PMC · via rucaparib

  9. New publication2022-10-10
    Overall survival in the OlympiA phase III trial of adjuvant olaparib in patients with germline pathogenic variants in BRCA1/2 and high-risk, early breast cancer.

    Annals of oncology : official journal of the European Society for Medical Oncology · 2022 · 325 citations · Europe PMC · via olaparib

  10. Safety communication2022-09-26

    Drug Safety Update: Rucaparib (Rubraca▼): withdrawal of third-line treatment indication

    mhra · safety · mhra · via rucaparib

  11. New publication2021-06-03
    Adjuvant Olaparib for Patients with <i>BRCA1</i>- or <i>BRCA2</i>-Mutated Breast Cancer.

    The New England journal of medicine · 2021 · 1,225 citations · Europe PMC · via olaparib

  12. Safety communication2020-10-22

    Drug Safety Update: Niraparib (Zejula▼): reports of severe hypertension and posterior reversible encephalopathy syndrome (PRES), particularly in early treatment

    mhra · safety · mhra · via niraparib

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.