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Protein / target

5-hydroxytryptamine receptor 1A

Encoded byHTR1AP08908Homo sapiensSwiss-Prot
Clinically validated
Therapeutic maturity
17
Approved medicines
Open Targets target-level
View by indication →
30
Clinical trials
Small-molecule tractable
Druggability
Approved Drug

Protein at a glance

Biological role

G protein-coupled serotonin receptor

Strongest disease association

Bipolar Disorder

Via encoding gene HTR1A · Genetic evidence · score 0.06

Therapeutic position

Established drug target

Small molecules

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

G protein-coupled receptor for 5-hydroxytryptamine (serotonin).

View complete UniProt function annotation

G protein-coupled receptor for 5-hydroxytryptamine (serotonin) (PubMed:22957663, PubMed:3138543, PubMed:33762731, PubMed:37935376, PubMed:37935377, PubMed:8138923, PubMed:8393041). Also functions as a receptor for various drugs and psychoactive substances (PubMed:22957663, PubMed:3138543, PubMed:33762731, PubMed:38552625, PubMed:8138923, PubMed:8393041). Ligand binding causes a conformation change that triggers signaling via guanine nucleotide-binding proteins (G proteins) and modulates the activity of downstream effectors, such as adenylate cyclase (PubMed:22957663, PubMed:3138543, PubMed:33762731, PubMed:8138923, PubMed:8393041). HTR1A is coupled to G(i)/G(o) G alpha proteins and mediates inhibitory neurotransmission: signaling inhibits adenylate cyclase activity and activates a phosphatidylinositol-calcium second messenger system that regulates the release of Ca(2+) ions from intracellular stores (PubMed:33762731, PubMed:35610220). Beta-arrestin family members regulate signaling by mediating both receptor desensitization and resensitization processes (PubMed:18476671, PubMed:20363322, PubMed:20945968). Plays a role in the regulation of 5-hydroxytryptamine release and in the regulation of dopamine and 5-hydroxytryptamine metabolism (PubMed:18476671, PubMed:20363322, PubMed:20945968). Plays a role in the regulation of dopamine and 5-hydroxytryptamine levels in the brain, and thereby affects neural activity, mood and behavior (PubMed:18476671, PubMed:20363322, PubMed:20945968). Plays a role in the response to anxiogenic stimuli (PubMed:18476671, PubMed:20363322, PubMed:20945968)

Subcellular location

Cell membraneCell projection, dendrite
Domains and Gene Ontology detail (23)

Gene Ontology

  • Cdendrite
  • Cplasma membrane
  • Csynapse
  • FG protein-coupled serotonin receptor activity
  • FGi/o-coupled serotonin receptor activity
  • Fneurotransmitter receptor activity
  • Freceptor-receptor interaction
  • Fserotonin binding
  • Fserotonin receptor activity
  • Padenylate cyclase-inhibiting serotonin receptor signaling pathway
  • Pbehavioral fear response
  • Pchemical synaptic transmission

422 aa · 46 kDa

Biological roles

Reactome v97

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

Inhibitory neurotransmissionUniProtCell proliferation & survivalGOG protein-coupled signallingUniProt · GOMetabolic enzyme activityGO
View supporting evidence

Inhibitory neurotransmission

  • ·G protein-coupled receptor for 5-hydroxytryptamine (serotonin) (PubMed:22957663, PubMed:…

Cell proliferation & survival

  • ·positive regulation of cell population proliferation

G protein-coupled signalling

  • ·G protein-coupled receptor for 5-hydroxytryptamine (serotonin) (PubMed:22957663, PubMed:…
  • ·G protein-coupled serotonin receptor activity
  • ·G protein-coupled receptor signaling pathway
  • ·G protein-coupled receptor signaling pathway, coupled to cyclic nucleotide second messen…

Metabolic enzyme activity

  • ·regulation of dopamine metabolic process
  • ·serotonin metabolic process
View underlying pathways (1)

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.

GNB1GNAI1SLC6A4FGFR1GNG2HTR2AHTR1BGALR1MAOAOXTHTR1A

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

2 medicines · 7 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.

Psychotic Disorders2 medicines
Schizophrenia2 medicines
Autistic Disorder1 medicine
Bipolar Disorder1 medicine
Depressive Disorder1 medicine
Psychomotor Agitation1 medicine
Tourette's Syndrome1 medicine

17 medicines meet Open Targets' target-level approved-medicine definition; the 2 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

2

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.

aripiprazole
Narrow target profileApprovedPartial agonist

Serotonin 1a (5-HT1a) receptor partial agonist

Indicated for Autistic Disorder, Bipolar Disorder, Depressive Disorder, Psychomotor Agitation

Direct interaction with this protein · 1 of 3 recorded protein targets — narrow recorded profile

brexpiprazole
Narrow target profileApprovedPartial agonist

Serotonin 1a (5-HT1a) receptor partial agonist

Indicated for Psychotic Disorders, Schizophrenia

Direct interaction with this protein · 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 HTR1A

Gene-level evidence surfaced through the gene HTR1Athat 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.

Major depressive disorder
0.78Well supported

Clinical evidence dominant · Open Targets 0.63

Schizophrenia
0.77Well supported

Clinical evidence dominant · Open Targets 0.62

Bipolar Disorder
0.76Well supported

Clinical evidence dominant · Open Targets 0.61

Anxiety Disorders
0.75Well supported

Clinical evidence dominant · Open Targets 0.61

Autistic Disorder
0.74Moderately supported

Clinical evidence dominant · Open Targets 0.60

View evidence synthesis (5)
Major depressive disorderWell supported
0.78
agreement 0.620.93
Clinical86%Literature14%

Open Targets aggregate 0.63 · 2 independent evidence families

SchizophreniaWell supported
0.77
agreement 0.620.93
Clinical89%Literature11%

Open Targets aggregate 0.62 · 2 independent evidence families

Bipolar DisorderWell supported
0.76
agreement 0.660.87
Clinical89%Genetic7%Literature4%

Open Targets aggregate 0.61 · 3 independent evidence families

Anxiety DisordersWell supported
0.75
agreement 0.590.91
Clinical96%Literature4%

Open Targets aggregate 0.61 · 2 independent evidence families

Autistic DisorderModerately supported
0.74
agreement 0.590.90
Clinical97%Literature3%

Open Targets aggregate 0.60 · 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 per-type scores above show the calculation.

Show all associations
Major depressive disorder0.63
Schizophrenia0.62
Bipolar Disorder0.61
Anxiety Disorders0.61
Autistic Disorder0.60
Psychotic disorder0.59
bipolar I disorder0.58
Depressive Disorder0.57
Tourette's Syndrome0.55

Drug development

35 compounds recorded · 17 approved · 16 in clinical development · 2 earlier-stage

Open Targets' development universe — every compound recorded against the target at any stage, not all approved medicines. Distinct from the 2 drugs that target this protein in Forefront's canonical graph (2 with a mapped approved indication, shown above): these count different sets and are not a subset relation.

View all recorded compounds (10)
BEFIRADOLPhase 2
DEXFENFLURAMINEApproval
GEPIRONE HYDROCHLORIDEApproval
ARIPIPRAZOLEApproval
ROBALZOTANPhase 2
VORTIOXETINE HYDROBROMIDEApproval
VILAZODONEApproval
VORTIOXETINEApproval
SARIZOTAN HYDROCHLORIDEPhase 2
LECOZOTAN HYDROCHLORIDEPhase 2 3

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 degradersEmerging

Feasibility evidence (database ubiquitination and small molecule binder) — no clinical-stage drug of this modality recorded.

Other modalitiesStrong

Approved Drug support this modality.

View underlying tractability evidence (10)
SM · Approved DrugSM · Structure with LigandSM · High-Quality LigandSM · Druggable FamilyAB · UniProt loc high confAB · GO CC high confAB · UniProt SigP or TMHMMPR · Database UbiquitinationPR · Small Molecule BinderOC · Approved Drug

Raw Open Targets tractability assessment buckets, by modality.

Safety-related annotations

increased locomotor activityLynch et al. (2017)decreased blood pressureLynch et al. (2017)decreased memoryLynch et al. (2017)decreased anxietyLynch et al. (2017)decreased body temperatureLynch et al. (2017)paresthesiaLynch et al. (2017)stereotypyLynch et al. (2017)increased heart rateLynch et al. (2017)cortisol secretionBowes et al. (2012)decreased/increased locomotor activityLynch et al. (2017)increased memoryLynch et al. (2017)methamphetamine psychosisClinPGx

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)

WITHDRAWN · via aripiprazole · NCT05554627

COMPLETED · via aripiprazole · NCT02146547

COMPLETED · via aripiprazole · NCT01446328

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 a drug that targets 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. Product recall2026-05-27

    Recall (Class II): ARIPIPRAZOLE

    fda · safety · fda · via aripiprazole

  2. New publication2024-08-26
    Long-Acting Injectable Antipsychotic Initiation in Child and Adolescent Patients with Psychiatric Disorders.

    Journal of child and adolescent psychopharmacology · 2025 · 4 citations · Europe PMC · via aripiprazole

  3. Safety communication2023-12-18

    Drug Safety Update: Aripiprazole (Abilify and generic brands): risk of pathological gambling

    mhra · safety · mhra · via aripiprazole

  4. New publication2015-12-01
    Cariprazine in acute exacerbation of schizophrenia: a fixed-dose, phase 3, randomized, double-blind, placebo- and active-controlled trial.

    The Journal of clinical psychiatry · 2015 · 124 citations · Europe PMC · via aripiprazole

  5. Regulatory approval2015-11-15

    Approval: Aripiprazole Accord (EMA)

    ema · regulatory · ema · via aripiprazole

  6. Regulatory approval2015-08-20

    Approval: Aripiprazole Sandoz (EMA)

    ema · regulatory · ema · via aripiprazole

  7. Regulatory approval2015-06-30

    Approval: Aripiprazole Mylan Pharma (previously Aripiprazole Pharmathen) (EMA)

    ema · regulatory · ema · via aripiprazole

  8. Regulatory approval2015-06-25

    Approval: Aripiprazole Zentiva (EMA)

    ema · regulatory · ema · via aripiprazole

  9. Regulatory approval2013-11-14

    Approval: Abilify Maintena (EMA)

    ema · regulatory · ema · via aripiprazole

  10. New publication2013-01-03
    Aripiprazole for the treatment of methamphetamine dependence: a randomized, double-blind, placebo-controlled trial.

    Addiction (Abingdon, England) · 2013 · 45 citations · Europe PMC · via aripiprazole

  11. New publication2011-11-29
    Double-blind, randomized, placebo-controlled long-term maintenance study of aripiprazole in children with bipolar disorder.

    The Journal of clinical psychiatry · 2012 · 40 citations · Europe PMC · via aripiprazole

  12. Regulatory approval2004-06-04

    Approval: Abilify (EMA)

    ema · regulatory · ema · via aripiprazole

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.