Protein / target

Neuronal acetylcholine receptor subunit alpha-4

CHRNA4P43681Homo sapiensSwiss-Prot
Clinically validated
Therapeutic maturity
3
Approved medicines
30
Clinical trials
Small-molecule tractable
Druggability
Approved Drug

Protein at a glance

Biological role

Acetylcholine-gated monoatomic cation-selective channel activity

Primary system

Nervous system

Strongest disease association

autosomal dominant nocturnal frontal lobe epilepsy

Genetic evidence · score 0.84

Therapeutic maturity

Clinically validated target

3 approved medicines against this target

Druggability

Small molecule

Open Targets tractability · Approved Drug

Clinical development

3 approved · 12 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

Component of neuronal acetylcholine receptors (nAChRs) that function as pentameric, ligand-gated cation channels with high calcium permeability among other activities. nAChRs are excitatory neurotrasnmitter receptors formed by a collection of nAChR subunits known to mediate synaptic transmission in the nervous system and the neuromuscular junction. Each nAchR subunit confers differential attributes to channel properties, including activation, deactivation and desensitization kinetics, pH sensitivity, cation permeability, and binding to allosteric modulators (PubMed:22361591, PubMed:27698419, PubMed:29720657, PubMed:38454578). CHRNA4 forms heteropentameric neuronal acetylcholine receptors with CHRNB2 and CHRNB4, as well as CHRNA5 and CHRNB3 as accesory subunits. Is the most abundant nAChR subtype expressed in the central nervous system (PubMed:16835356, PubMed:22361591, PubMed:27698419, PubMed:29720657, PubMed:38454578). Found in two major stoichiometric forms,(CHRNA4)3:(CHRNB2)2 and (CHRNA4)2:(CHRNB2)3, the two stoichiometric forms differ in their unitary conductance, calcium permeability, ACh sensitivity and potentiation by divalent cation (PubMed:27698419, PubMed:29720657, PubMed:38454578). Involved in the modulation of calcium-dependent signaling pathways, influences the release of neurotransmitters, including dopamine, glutamate and GABA (By similarity)

Subcellular location

Synaptic cell membraneCell membrane
Domains and Gene Ontology detail (40)

Gene Ontology

  • Cacetylcholine-gated channel complex
  • Ccation channel complex
  • Cdendrite
  • Cexternal side of plasma membrane
  • Cmembrane
  • Cneuron projection
  • Cneuronal cell body
  • Cneurotransmitter receptor complex
  • Cplasma membrane
  • Cpostsynaptic membrane
  • Cpresynaptic membrane
  • Csynapse

627 aa · 70 kDa · 2 isoforms

Biological roles

Reactome v97

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

Synaptic signallingUniProt · GO · ReactomeLigand-gated signallingUniProt · GOIon channel gatingGOInhibitory neurotransmissionGOImmune signallingGO
View supporting evidence

Synaptic signalling

  • ·Component of neuronal acetylcholine receptors (nAChRs) that function as pentameric, liga…
  • ·neurotransmitter receptor complex
  • ·postsynaptic membrane
  • ·presynaptic membrane

Ligand-gated signalling

  • ·Component of neuronal acetylcholine receptors (nAChRs) that function as pentameric, liga…
  • ·ligand-gated monoatomic ion channel activity

Ion channel gating

  • ·acetylcholine-gated channel complex
  • ·ligand-gated monoatomic ion channel activity
  • ·monoatomic ion transmembrane transport

Inhibitory neurotransmission

  • ·inhibitory postsynaptic potential

Immune signalling

  • ·B cell activation
View underlying pathways (3)

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.

CHRNB2CHRNA2CHRNA7KCNQ2CHRNB4CHRNA9CHRNA3JAK2CHRNA6CHRNA5CHRNA4

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

2

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.

Nicotine
ApprovedAgonist

Neuronal acetylcholine receptor; alpha4/beta2 agonist

Appears in clinical studies involving nicotine dependence, non-small cell lung carcinoma, smoking cessation, nicotine dependence

Acts on a complex — shared with CHRNB2 · 1 of 2 recorded protein targets — narrow recorded profile

Mecamylamine
Antagonist

Neuronal acetylcholine receptor; alpha4/beta2 antagonist

Acts on a complex — shared with CHRNB2 · 1 of 2 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.

Strongest genetic associations

Human genetic evidence — the most direct causal link between this target and a disease.

autosomal dominant nocturnal frontal lobe epilepsy0.84

Genetic · overall 0.71

chronic obstructive pulmonary disease0.82

Genetic · overall 0.59

nicotine dependence0.77

Genetic · overall 0.73

smoking cessation0.72

Genetic · overall 0.54

smoking initiation0.71

Genetic · overall 0.43

Highest-confidence therapeutic associations

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

smoking behavior0.69

Clinical · overall 0.42

lung cancer0.40

Clinical · overall 0.43

Highest overall evidence

Remaining associations by Open Targets' aggregated evidence score.

familial sleep-related hypermotor epilepsy0.51

Animal model

hereditary disease0.42

Genetic

chronic lung disease0.41

Genetic

Show all associations
nicotine dependence0.73
autosomal dominant nocturnal frontal lobe epilepsy0.71
chronic obstructive pulmonary disease0.59
smoking cessation0.54
familial sleep-related hypermotor epilepsy0.51
smoking initiation0.43
lung cancer0.43
smoking behavior0.42
hereditary disease0.42
chronic lung disease0.41

Open Targets ranks 502 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 · 16 total

SIMPINICLINEPhase 2

irritable bowel syndrome · dry eye syndrome · gastroparesis

ABT-560Phase 1

Cognitive impairment

POZANICLINEPhase 2

anxiety disorder · attention deficit-hyperactivity disorder · dementia

DEXMECAMYLAMINEPhase 3

major depressive disorder · overactive bladder · Hyperhidrosis

NICOTINEApproval

nicotine dependence · non-small cell lung carcinoma · smoking cessation

NICOTINE POLACRILEXPhase 3

smoking behavior · pregnancy · nicotine dependence

VARENICLINE TARTRATEPhase 3

smoking cessation · nicotine dependence · ventricular tachycardia

DIANICLINEPhase 3

nicotine dependence

CP-601927Phase 2

gastrointestinal disease · major depressive disorder

ISPRONICLINEPhase 2

Alzheimer disease · schizophrenia · Alzheimer disease

Tractability

SM · Approved DrugSM · Structure with LigandSM · High-Quality LigandSM · Druggable FamilyAB · GO CC high confAB · UniProt loc med confAB · UniProt SigP or TMHMMPR · Small Molecule Binder

Safety liabilities

nicotine dependenceparalysisconstipationdecreased heart ratemuscle relaxationalcoholismnauseaapnoeapalpitationssuccessfully quit smokingabuse potentialanalgesia

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 Mecamylamine · NCT00262470

COMPLETED · via Nicotine · NCT00468234

COMPLETED · via Mecamylamine · NCT00455650

COMPLETED · via Nicotine · NCT00625131

COMPLETED · via Nicotine · NCT01400243

COMPLETED · via Nicotine · NCT00573248

COMPLETED · via Nicotine · NCT01830842

COMPLETED · via Nicotine · NCT01596556

COMPLETED · via Mecamylamine · NCT00018161

COMPLETED · via Nicotine · NCT01702519

RECRUITING · via Nicotine · NCT07585006

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.

nicotine dependenceWell supported
0.94
agreement 0.841.00
Genetic49%Clinical47%Literature4%

Open Targets aggregate 0.73 · 3 independent evidence families

chronic obstructive pulmonary diseaseWell supported
0.90
agreement 0.801.00
Genetic63%Clinical35%Literature3%

Open Targets aggregate 0.59 · 3 independent evidence families

autosomal dominant nocturnal frontal lobe epilepsyWell supported
0.89
agreement 0.771.00
Genetic70%Animal model27%Literature3%Genetic literaturedup

Open Targets aggregate 0.71 · 3 independent evidence families · 1 not counted as duplicate

smoking cessationWell supported
0.86
agreement 0.760.96
Genetic58%Clinical42%

Open Targets aggregate 0.54 · 2 independent evidence families

lung cancerModerately supported
0.73
agreement 0.620.84
Genetic64%Clinical32%Literature4%

Open Targets aggregate 0.43 · 3 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

10

Recent activity around this target, drawn from one canonical event stream. Every item is reached through 2 drugs that target this protein, so each event is news about that drug rather than about the protein directly.

  1. Regulatory action2026-07-14
    FDA authorized Zyn nicotine pouches without knowing what they were made of, says former agency scientist

    STAT News · news · via Nicotine

  2. Industry development2026-06-17
    Should nicotine be regulated like a narcotic? A Pacific nation makes the case

    Nature News · news · via Nicotine

  3. New publication2024-02-20
    Electronic cigarettes and cardiovascular disease: epidemiological and biological links.

    Pflugers Archiv : European journal of physiology · 2024 · 16 citations · Europe PMC · via Nicotine

  4. New publication2021-05-23
    A Pilot Randomized Trial of Transdermal Nicotine for Pulmonary Sarcoidosis.

    Chest · 2021 · 25 citations · Europe PMC · via Nicotine

  5. New publication2020-10-07
    Design, rationale, and baseline characteristics of a pilot randomized clinical trial of nicotine treatment for pulmonary sarcoidosis.

    Contemporary clinical trials communications · 2020 · 5 citations · Europe PMC · via Nicotine

  6. New publication2012-11-14
    Nicotine replacement therapy for smoking cessation.

    The Cochrane database of systematic reviews · 2012 · 476 citations · Europe PMC · via Nicotine

  7. New publication2012-10-29
    Nicotine related brain activity: the influence of smoking history and blood nicotine levels, an exploratory study.

    Drug and alcohol dependence · 2013 · 14 citations · Europe PMC · via Nicotine

  8. New publication2009-12-01
    Effects of transdermal nicotine on symptoms, moods, and cardiovascular activity in the everyday lives of smokers and nonsmokers with attention-deficit/hyperactivity disorder.

    Psychology of addictive behaviors : journal of the Society of Psychologists in Addictive Behaviors · 2009 · 37 citations · Europe PMC · via Nicotine

  9. New publication2008-12-01
    Picomolar amyloid-beta positively modulates synaptic plasticity and memory in hippocampus.

    The Journal of neuroscience : the official journal of the Society for Neuroscience · 2008 · 580 citations · Europe PMC · via Mecamylamine

  10. New publication2001-10-01
    The brain metabolite kynurenic acid inhibits alpha7 nicotinic receptor activity and increases non-alpha7 nicotinic receptor expression: physiopathological implications.

    The Journal of neuroscience : the official journal of the Society for Neuroscience · 2001 · 691 citations · Europe PMC · via Nicotine

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.