Seroatlas · Human Serome Atlas

IL21

Interleukin-21

Also known as: IL-21, IL21_HUMAN, Za11

Cross-references: UniProt · Ensembl · Human Protein Atlas · GeneCards · NCBI Gene

Protein identityUniProt · HPA

UniProt accession
Q9HBE4
Gene
IL21
Ensembl
ENSG00000138684
Chromosome
4
Canonical length
162 aa
Protein class
Disease related genes, Human disease related genes, Plasma proteins, Predicted secreted proteins
Secretome location
Secreted to blood

OverviewNCBI Gene

This gene encodes a member of the common-gamma chain family of cytokines with immunoregulatory activity. The encoded protein plays a role in both the innate and adaptive immune responses by inducing the differentiation, proliferation and activity of multiple target cells including macrophages, natural killer cells, B cells and cytotoxic T cells. Dysregulation of this gene plays a role in multiple immune-mediated diseases including lupus, psoriasis and chronic inflammatory diseases. Alternatively spliced transcript variants encoding multiple isoforms have been observed for this gene. [provided by RefSeq, Dec 2011]

Canonical amino-acid sequenceUniProt

162 residues, UniProt reviewed canonical sequence.

>Q9HBE4|IL21
     1  MRSSPGNMER IVICLMVIFL GTLVHKSSSQ GQDRHMIRMR QLIDIVDQLK NYVNDLVPEF
    61  LPAPEDVETN CEWSAFSCFQ KAQLKSANTG NNERIINVSI KKLKRKPPST NAGRRQKHRL
   121  TCPSCDSYEK KPPKEFLERF KSLLQKMIHQ HLSSRTHGSE DS

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against IL21 can act on the native protein depends on physical access: surface and secreted proteins are reachable by circulating antibodies, intracellular proteins usually are not.

Antibody reachability
Secreted
Secreted
Yes
Transmembrane segments
0
Mean surface accessibility (rSASA)
0.38
Highest tissue expression
5.5 nTPM

Expression across tissuesHPA

Tissue

  • lymph node: 5.5 nTPM
  • tonsil: 2.6 nTPM
  • appendix: 0.9 nTPM
  • testis: 0.7 nTPM
  • urinary bladder: 0.2 nTPM
  • small intestine: 0.1 nTPM

Single-cell type

  • early spermatids: 17 nCPM
  • late primary spermatocytes: 8.7 nCPM
  • late spermatids: 8.6 nCPM
  • t-cells: 3 nCPM
  • foveolar cells: 0.3 nCPM
  • mesothelial cells: 0.3 nCPM

Immune cell

  • memory CD4 T-cell: 0.2 nTPM
  • basophil: 0 nTPM
  • classical monocyte: 0 nTPM
  • eosinophil: 0 nTPM
  • gdT-cell: 0 nTPM
  • intermediate monocyte: 0 nTPM

Brain region

  • amygdala: 0 nTPM
  • basal ganglia: 0 nTPM
  • cerebellum: 0 nTPM
  • cerebral cortex: 0 nTPM
  • choroid plexus: 0 nTPM
  • hippocampal formation: 0 nTPM

DiseaseUniProt · ClinVar · IEDB · PubMed

Four sources answering four different questions about IL21.

Disease | AllUniProt

Conditions IL21 is implicated in, by any mechanism.

  • Immunodeficiency, common variable, 11 (CVID11) MIM:615767

Disease | GeneticClinVar

1 pathogenic / likely-pathogenic of 126 ClinVar records.

Conditions with pathogenic or likely-pathogenic variants.

  • IL21-related infantile inflammatory bowel disease

Genetic constraint and essentialitygnomAD · DepMap

Does the body need this protein intact? Low LOEUF or a strong DepMap dependency means loss or blockade of the protein is likely to be felt.

gnomAD LOEUF (loss-of-function intolerance)
0.64
gnomAD pLI
0.63
gnomAD missense Z
1.54
DepMap mean gene effect
0.07
DepMap dependency class
none

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 3% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).

OntologyGO

Biological processes

Molecular functions

Cellular components

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads IL21 as an antibody target. Whether an autoantibody or antibody against IL21 could matter depends on whether native IL21 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

IL21 is annotated as secreted, so native IL21 circulates and is directly accessible to antibodies. Secreted and cell-surface proteins are the autoantibody targets most likely to act like drugs, blocking or depleting the native protein.

Annotation status

The present source text does not explicitly label IL21 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/IL21. Study-independent annotations aggregated from UniProt, Human Protein Atlas, PubMed, IEDB, Pfam, InterPro, Gene Ontology, AlphaFold, gnomAD, DepMap, ClinVar, TCGA. Catalog release seroatlas-reviewed-human-uniprot-20260313.

Seroatlas is the reference for exploring autoantibody and antibody serology at the human-protein level: the autoreactome and human serome, multiplex serology (HuProt, HuScan, VirScan, PhIP-Seq).

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