Protein / target

Interleukin-23 subunit alpha

IL23AQ9NPF7Homo sapiensSwiss-Prot
Clinically validated
Therapeutic maturity
6
Approved medicines
30
Clinical trials
Small-molecule tractable
Druggability
Structure with Ligand

Protein at a glance

Biological role

Interleukin-23 receptor binding

Primary system

Immune system

Strongest disease association

psoriasis

Genetic evidence · score 0.39

Therapeutic maturity

Clinically validated target

6 approved medicines against this target

Druggability

Small molecule

Open Targets tractability · Structure with Ligand

Clinical development

6 approved · 2 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

Associates with IL12B to form the pro-inflammatory cytokine IL-23 that plays different roles in innate and adaptive immunity (PubMed:11114383). Released by antigen-presenting cells such as dendritic cells or macrophages, binds to a heterodimeric receptor complex composed of IL12RB1 and IL23R to activate JAK2 and TYK2 which then phosphorylate the receptor to form a docking site leading to the phosphorylation of STAT3 and STAT4 (PubMed:29287995, PubMed:32474165, PubMed:33606986). This process leads to activation of several pathways including p38 MAPK or NF-kappa-B and promotes the production of pro-inflammatory cytokines such as interleukin-17A/IL17A (PubMed:12023369). In turn, participates in the early and effective intracellular bacterial clearance (PubMed:32474165). Promotes the expansion and survival of T-helper 17 cells, a CD4-positive helper T-cell subset that produces IL-17, as well as other IL-17-producing cells (PubMed:17676044)

Subcellular location

Secreted
Domains and Gene Ontology detail (38)

Gene Ontology

  • Cendoplasmic reticulum lumen
  • Cextracellular region
  • Cextracellular space
  • Cinterleukin-23 complex
  • Fcytokine activity
  • Finterleukin-23 receptor binding
  • Pcell surface receptor signaling pathway via JAK-STAT
  • Pcell surface receptor signaling pathway via STAT
  • Pdefense response to Gram-negative bacterium
  • Pdefense response to virus
  • Pinflammatory response
  • Pinnate immune response

189 aa · 21 kDa

Biological roles

Reactome v97

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

Immune signallingUniProt · GO · ReactomeKinase signallingUniProt
View supporting evidence

Immune signalling

  • ·Associates with IL12B to form the pro-inflammatory cytokine IL-23 that plays different r…
  • ·interleukin-23 complex
  • ·cytokine activity
  • ·interleukin-23 receptor binding

Kinase signalling

  • ·Associates with IL12B to form the pro-inflammatory cytokine IL-23 that plays different r…
View underlying pathways (2)

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.

IL12BIL23RIL12RB1TYK2JAK2IL12RB2IL17FIL17AIL22IL6IL23A

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

1

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.

guselkumab
ApprovedInhibitor

Interleukin-23 inhibitor

Appears in clinical studies involving psoriasis vulgaris, psoriatic arthritis, psoriasis, psoriasis vulgaris

Acts on a complex — shared with IL12B · 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.

psoriasis0.39

Genetic · overall 0.68

psoriasis vulgaris0.24

Genetic · overall 0.64

Highest-confidence therapeutic associations

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

Crohn disease0.99

Clinical · overall 0.61

psoriatic arthritis0.98

Clinical · overall 0.60

ulcerative colitis0.98

Clinical · overall 0.61

immune system disorder0.91

Clinical · overall 0.55

pustular psoriasis0.76

Clinical · overall 0.46

Highest overall evidence

Remaining associations by Open Targets' aggregated evidence score.

psoriasis-related juvenile idiopathic arthritis0.38

Clinical

palmoplantar pustulosis0.36

Clinical

generalized pustular psoriasis0.35

Clinical

Show all associations
psoriasis0.68
psoriasis vulgaris0.64
Crohn disease0.61
ulcerative colitis0.61
psoriatic arthritis0.60
immune system disorder0.55
pustular psoriasis0.46
psoriasis-related juvenile idiopathic arthritis0.38
palmoplantar pustulosis0.36
generalized pustular psoriasis0.35

Open Targets ranks 663 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 · 8 total

GUSELKUMABApproval

psoriasis vulgaris · psoriatic arthritis · psoriasis

BRIAKINUMABApproval

immune system disorder · psoriasis vulgaris · psoriasis

USTEKINUMABApproval

psoriasis vulgaris · psoriatic arthritis · Crohn disease

EBDAROKIMABPhase 3

psoriasis vulgaris · psoriasis · ulcerative colitis

TILDRAKIZUMABApproval

psoriasis vulgaris · psoriasis vulgaris · psoriasis

MIRIKIZUMABApproval

Crohn disease · ulcerative colitis · ulcerative colitis

BRAZIKUMABPhase 3

Crohn disease · Crohn disease · ulcerative colitis

RISANKIZUMABApproval

Crohn disease · psoriatic arthritis · psoriasis

Tractability

SM · Structure with LigandAB · Approved DrugAB · UniProt loc high confAB · GO CC high confAB · UniProt SigP or TMHMM

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)

RECRUITING · via guselkumab · NCT05858632

ClinicalTrials.gov via the drug-target graph.

Related literature

1

Papers indexed under “Interleukin-23 Subunit p19” — a subject heading that covers this protein without being specific to it. Shown as context; not counted as this protein's own research activity.

The IL-23/IL-17 axis in inflammation.

Iwakura Y · The Journal of clinical investigation · 2006

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

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.

psoriasisWell supported
0.87
agreement 0.770.97
Clinical57%Genetic30%Literature11%RNA expression2%

Open Targets aggregate 0.68 · 4 independent evidence families

psoriasis vulgarisWell supported
0.81
agreement 0.700.91
Clinical74%Genetic24%Literature2%

Open Targets aggregate 0.64 · 3 independent evidence families

ulcerative colitisWell supported
0.76
agreement 0.620.89
Clinical91%RNA expression5%Literature4%

Open Targets aggregate 0.61 · 3 independent evidence families

Crohn diseaseWell supported
0.75
agreement 0.620.89
Clinical94%Literature5%RNA expression1%

Open Targets aggregate 0.61 · 3 independent evidence families

psoriatic arthritisModerately supported
0.75
agreement 0.590.90
Clinical96%Literature4%

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

What's happening now

4

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

  1. Industry development2026-06-09
    AbbVie’s Skyrizi narrowly slides ahead of J&J’s Tremfya in May drug ad spending rankings

    Fierce Pharma · news · via guselkumab

  2. New publication2024-03-15
    Comparative Effectiveness of Bimekizumab and Guselkumab in Patients with Psoriatic Arthritis at 52 Weeks Assessed Using a Matching-Adjusted Indirect Comparison.

    Rheumatology and therapy · 2024 · 3 citations · Europe PMC · via guselkumab

  3. Regulatory approval2017-11-10

    Approval: Tremfya (EMA)

    ema · regulatory · ema · via guselkumab

  4. New publication2017-01-02
    Efficacy and safety of guselkumab, an anti-interleukin-23 monoclonal antibody, compared with adalimumab for the continuous treatment of patients with moderate to severe psoriasis: Results from the phase III, double-blinded, placebo- and active comparator-controlled VOYAGE 1 trial.

    Journal of the American Academy of Dermatology · 2017 · 617 citations · Europe PMC · via guselkumab

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.