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Protein / target

Potassium-transporting ATPase alpha chain 1

Encoded byATP4AP20648Homo sapiensSwiss-Prot
Clinically validated
Therapeutic maturity
16
Approved medicines
Open Targets target-level
View by indication →
30
Clinical trials
Small-molecule tractable
Druggability
Approved Drug

Protein at a glance

Biological role

P-type sodium:potassium-exchanging transporter

Strongest disease association

Gastroesophageal Reflux

Via encoding gene ATP4A · Clinical evidence · score 0.61

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

The catalytic subunit of the gastric H(+)/K(+) ATPase pump which transports H(+) ions in exchange for K(+) ions across the apical membrane of parietal cells.

View complete UniProt function annotation

The catalytic subunit of the gastric H(+)/K(+) ATPase pump which transports H(+) ions in exchange for K(+) ions across the apical membrane of parietal cells. Uses ATP as an energy source to pump H(+) ions to the gastric lumen while transporting K(+) ion from the lumen into the cell (By similarity). Remarkably generates a million-fold proton gradient across the gastric parietal cell membrane, acidifying the gastric juice down to pH 1 (By similarity). Within a transport cycle, the transfer of a H(+) ion across the membrane is coupled to ATP hydrolysis and is associated with a transient phosphorylation that shifts the pump conformation from inward-facing (E1) to outward-facing state (E2). The release of the H(+) ion in the stomach lumen is followed by binding of K(+) ion converting the pump conformation back to the E1 state (By similarity)

Subcellular location

Apical cell membrane
Domains and Gene Ontology detail (15)

Gene Ontology

  • Capical plasma membrane
  • Cextracellular space
  • Cplasma membrane
  • FATP binding
  • FATP hydrolysis activity
  • Fmagnesium ion binding
  • FP-type potassium:proton transporter activity
  • FP-type sodium:potassium-exchanging transporter activity
  • Fpotassium ion binding
  • Pintracellular potassium ion homeostasis
  • Pintracellular sodium ion homeostasis
  • Pmonoatomic ion transmembrane transport

1035 aa · 114 kDa

Biological roles

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

Ion channel gatingGO
View supporting evidence

Ion channel gating

  • ·monoatomic ion transmembrane transport

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

Approved medicines with mapped indications

1 medicine · 1 area

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.

Gastroesophageal Reflux1 medicine

16 medicines meet Open Targets' target-level approved-medicine definition; the 1 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

1

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.

lansoprazole
ApprovedInhibitor

Potassium-transporting ATPase inhibitor

Indicated for Gastroesophageal Reflux

Acts on a complex — shared with ATP4B · 1 of 2 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 ATP4A

Gene-level evidence surfaced through the gene ATP4Athat 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.

Gastroesophageal Reflux
0.75Well supported

Clinical evidence dominant · Open Targets 0.61

Duodenal ulcer
0.74Moderately supported

Clinical evidence dominant · Open Targets 0.60

Gastrinoma
0.73Moderately supported

Clinical evidence dominant · Open Targets 0.59

Dyspepsia
0.71Moderately supported

Clinical evidence dominant · Open Targets 0.58

Arthritis, Rheumatoid
0.67Moderately supported

Clinical evidence dominant · Open Targets 0.54

View evidence synthesis (5)
Gastroesophageal RefluxWell supported
0.75
agreement 0.600.91
Clinical98%Literature2%

Open Targets aggregate 0.61 · 2 independent evidence families

Duodenal ulcerModerately supported
0.74
agreement 0.590.90
Clinical100%Literature0%

Open Targets aggregate 0.60 · 2 independent evidence families

GastrinomaModerately supported
0.73
agreement 0.580.89
Clinical100%Literature0%

Open Targets aggregate 0.59 · 2 independent evidence families

DyspepsiaModerately supported
0.71
agreement 0.560.87
Clinical99%Literature1%

Open Targets aggregate 0.58 · 2 independent evidence families

Arthritis, RheumatoidModerately supported
0.67
agreement 0.510.82
Clinical99%Literature1%

Open Targets aggregate 0.54 · 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
Gastroesophageal Reflux0.61
Duodenal ulcer0.60
Gastrinoma0.59
Dyspepsia0.58
Arthritis, Rheumatoid0.54

Drug development

17 compounds recorded · 16 approved · 1 in clinical development

Open Targets' development universe — every compound recorded against the target at any stage, not all approved medicines. Distinct from the 1 drug that targets this protein in Forefront's canonical graph (1 with a mapped approved indication, shown above): these count different sets and are not a subset relation.

View all recorded compounds (10)
ESOMEPRAZOLE STRONTIUMApproval
OMEPRAZOLEApproval
OMEPRAZOLE MAGNESIUMPhase 3
TEGOPRAZANApproval
VONOPRAZAN FUMARATEApproval
ABEPRAZANApproval
ESOMEPRAZOLE MAGNESIUMApproval
ESOMEPRAZOLE SODIUMApproval
LANSOPRAZOLEApproval
RABEPRAZOLE SODIUMApproval

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 Druggable Family 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.

View underlying tractability evidence (7)
SM · Approved DrugSM · Druggable FamilyAB · UniProt loc high confAB · GO CC high confAB · UniProt SigP or TMHMMPR · Database UbiquitinationPR · Small Molecule Binder

Raw Open Targets tractability assessment buckets, by modality.

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)

COMPLETED · via lansoprazole · NCT04248335

COMPLETED · via lansoprazole · NCT03124420

COMPLETED · via lansoprazole · NCT01667718

ClinicalTrials.gov via the drug-target graph.

What's happening now

3

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. New publication2012-01-01
    Lansoprazole for children with poorly controlled asthma: a randomized controlled trial.

    JAMA · 2012 · 156 citations · Europe PMC · via lansoprazole

  2. New publication2010-02-27
    Validation of the PAGI-SYM and PAGI-QOL among healing and maintenance of erosive esophagitis clinical trial participants.

    Quality of life research : an international journal of quality of life aspects of treatment, care and rehabilitation · 2010 · 12 citations · Europe PMC · via lansoprazole

  3. New publication2009-04-01
    Clinical trials: healing of erosive oesophagitis with dexlansoprazole MR, a proton pump inhibitor with a novel dual delayed-release formulation--results from two randomized controlled studies.

    Alimentary pharmacology & therapeutics · 2009 · 81 citations · Europe PMC · via lansoprazole

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.