Seroatlas · Human Serome Atlas

ISG20

Interferon-stimulated gene 20 kDa protein

Also known as: CD25, HEM45, ISG20_HUMAN

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

Protein identityUniProt · HPA

UniProt accession: Q96AZ6
Gene: ISG20
Ensembl: ENSG00000172183
Chromosome: 15
Canonical length: 181 aa
Protein class: Enzymes, Predicted intracellular proteins

OverviewNCBI Gene

Enables 3'-5' exonuclease activity and RNA binding activity. Involved in defense response to virus; negative regulation of viral genome replication; and nucleobase-containing compound catabolic process. Located in cytoplasm and nuclear lumen. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

181 residues, UniProt reviewed canonical sequence.

>Q96AZ6|ISG20
     1  MAGSREVVAM DCEMVGLGPH RESGLARCSL VNVHGAVLYD KFIRPEGEIT DYRTRVSGVT
    61  PQHMVGATPF AVARLEILQL LKGKLVVGHD LKHDFQALKE DMSGYTIYDT STDRLLWREA
   121  KLDHCRRVSL RVLSERLLHK SIQNSLLGHS SVEDARATME LYQISQRIRA RRGLPRLAVS
   181  D

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against ISG20 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: Intracellular
Secreted: No
Transmembrane segments: 0
Mean surface accessibility (rSASA): 0.28
Highest tissue expression: 177 nTPM

Expression across tissuesHPA

Tissue

lymph node: 177 nTPM
spleen: 140 nTPM
thymus: 81 nTPM
appendix: 74 nTPM
duodenum: 73 nTPM
stomach: 65 nTPM

Single-cell type

plasma cells: 1,105 nCPM
esophageal apical cells: 725 nCPM
endometrial ciliated cells: 323 nCPM
b-cells: 321 nCPM
t-cells: 318 nCPM
nk-cells: 306 nCPM

Immune cell

neutrophil: 1,347 nTPM
T-reg: 1,248 nTPM
naive B-cell: 1,191 nTPM
memory B-cell: 1,155 nTPM
memory CD4 T-cell: 511 nTPM
memory CD8 T-cell: 433 nTPM

Brain region

cerebral cortex: 15 nTPM
medulla oblongata: 13 nTPM
thalamus: 11 nTPM
white matter: 10 nTPM
basal ganglia: 9.6 nTPM
pons: 8.9 nTPM

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): 1.69
gnomAD pLI: 0
gnomAD missense Z: 0.21
DepMap mean gene effect: 0.01
DepMap dependency class: selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 4% 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 ISG20 as an antibody target. Whether an autoantibody or antibody against ISG20 could matter depends on whether native ISG20 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

ISG20 is annotated as predominantly intracellular. Intracellular proteins are common autoantibody markers, becoming visible to the immune system after cell injury or altered processing, but are usually markers of disease rather than direct drivers.

Annotation status

The present source text does not explicitly label ISG20 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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