Seroatlas · Human Serome Atlas

API5

Apoptosis inhibitor 5

Also known as: AAC-11, AAC11, API5_HUMAN, API5L1

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

Protein identityUniProt · HPA

UniProt accession
Q9BZZ5
Gene
API5
Ensembl
ENSG00000166181
Chromosome
11
Canonical length
524 aa
Protein class
Predicted intracellular proteins
Subcellular location
Nuclear speckles

OverviewNCBI Gene

This gene encodes an apoptosis inhibitory protein whose expression prevents apoptosis after growth factor deprivation. This protein suppresses the transcription factor E2F1-induced apoptosis and also interacts with, and negatively regulates Acinus, a nuclear factor involved in apoptotic DNA fragmentation. Its depletion enhances the cytotoxic action of the chemotherapeutic drugs. Multiple alternatively spliced transcript variants encoding different isoforms have been identified. [provided by RefSeq, Aug 2011]

Canonical amino-acid sequenceUniProt

524 residues, UniProt reviewed canonical sequence.

>Q9BZZ5|API5
     1  MPTVEELYRN YGILADATEQ VGQHKDAYQV ILDGVKGGTK EKRLAAQFIP KFFKHFPELA
    61  DSAINAQLDL CEDEDVSIRR QAIKELPQFA TGENLPRVAD ILTQLLQTDD SAEFNLVNNA
   121  LLSIFKMDAK GTLGGLFSQI LQGEDIVRER AIKFLSTKLK TLPDEVLTKE VEELILTESK
   181  KVLEDVTGEE FVLFMKILSG LKSLQTVSGR QQLVELVAEQ ADLEQTFNPS DPDCVDRLLQ
   241  CTRQAVPLFS KNVHSTRFVT YFCEQVLPNL GTLTTPVEGL DIQLEVLKLL AEMSSFCGDM
   301  EKLETNLRKL FDKLLEYMPL PPEEAENGEN AGNEEPKLQF SYVECLLYSF HQLGRKLPDF
   361  LTAKLNAEKL KDFKIRLQYF ARGLQVYIRQ LRLALQGKTG EALKTEENKI KVVALKITNN
   421  INVLIKDLFH IPPSYKSTVT LSWKPVQKVE IGQKRASEDT TSGSPPKKSS AGPKRDARQI
   481  YNPPSGKYSS NLGNFNYEQR GAFRGSRGGR GWGTRGNRSR GRLY

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against API5 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)
0.33
Highest tissue expression
58 nTPM

Expression across tissuesHPA

Tissue

  • thymus: 58 nTPM
  • liver: 54 nTPM
  • tonsil: 54 nTPM
  • lymph node: 50 nTPM
  • thyroid gland: 48 nTPM
  • kidney: 46 nTPM

Single-cell type

  • erythrocyte progenitors: 100 nCPM
  • mucous neck cells: 84 nCPM
  • neutrophil progenitors: 82 nCPM
  • innate lymphoid cells: 79 nCPM
  • pancreatic acinar cells: 78 nCPM
  • monocyte progenitors: 78 nCPM

Immune cell

  • NK-cell: 117 nTPM
  • total PBMC: 89 nTPM
  • MAIT T-cell: 75 nTPM
  • memory CD8 T-cell: 69 nTPM
  • naive CD8 T-cell: 69 nTPM
  • non-classical monocyte: 68 nTPM

Brain region

  • cerebellum: 69 nTPM
  • white matter: 68 nTPM
  • cerebral cortex: 58 nTPM
  • spinal cord: 58 nTPM
  • pons: 54 nTPM
  • hypothalamus: 54 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)
0.14
gnomAD pLI
1
gnomAD missense Z
2.92
DepMap mean gene effect
-0.17
DepMap dependency class
selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 5% 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

InteractionsUniProt · HPA

Protein binding partners of API5 in the human serome: UniProt-annotated complex subunits plus reported interactors. Each links to its own Seroatlas record.

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads API5 as an antibody target. Whether an autoantibody or antibody against API5 could matter depends on whether native API5 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

API5 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 API5 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/API5. 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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