Seroatlas · Human Serome Atlas

SAP18

Histone deacetylase complex subunit SAP18

Also known as: 2HOR0202, MGC27131, SAP18_HUMAN, SAP18p

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

Protein identityUniProt · HPA

UniProt accession
O00422
Gene
SAP18
Ensembl
ENSG00000150459
Chromosome
13
Canonical length
153 aa
Protein class
Predicted intracellular proteins, Transporters
Subcellular location
Nucleoplasm,Nuclear bodies,Cytosol

OverviewNCBI Gene

Histone acetylation plays a key role in the regulation of eukaryotic gene expression. Histone acetylation and deacetylation are catalyzed by multisubunit complexes. The protein encoded by this gene is a component of the histone deacetylase complex, which includes SIN3, SAP30, HDAC1, HDAC2, RbAp46, RbAp48, and other polypeptides. This protein directly interacts with SIN3 and enhances SIN3-mediated transcriptional repression when tethered to the promoter. A pseudogene has been identified on chromosome 2. [provided by RefSeq, Dec 2008]

Canonical amino-acid sequenceUniProt

153 residues, UniProt reviewed canonical sequence.

>O00422|SAP18
     1  MAVESRVTQE EIKKEPEKPI DREKTCPLLL RVFTTNNGRH HRMDEFSRGN VPSSELQIYT
    61  WMDATLKELT SLVKEVYPEA RKKGTHFNFA IVFTDVKRPG YRVKEIGSTM SGRKGTDDSM
   121  TLQSQKFQIG DYLDIAITPP NRAPPPSGRM RPY

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against SAP18 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)
0.39
Highest tissue expression
292 nTPM

Expression across tissuesHPA

Tissue

  • spinal cord: 292 nTPM
  • skeletal muscle: 280 nTPM
  • bone marrow: 228 nTPM
  • midbrain: 222 nTPM
  • hypothalamus: 209 nTPM
  • kidney: 193 nTPM

Single-cell type

  • late primary spermatocytes: 1,513 nCPM
  • oocytes: 1,359 nCPM
  • early spermatids: 1,229 nCPM
  • esophageal apical cells: 1,097 nCPM
  • syncytiotrophoblasts: 1,064 nCPM
  • esophageal suprabasal cells: 689 nCPM

Immune cell

  • total PBMC: 912 nTPM
  • plasmacytoid DC: 571 nTPM
  • non-classical monocyte: 551 nTPM
  • eosinophil: 543 nTPM
  • T-reg: 519 nTPM
  • memory B-cell: 496 nTPM

Brain region

  • white matter: 179 nTPM
  • spinal cord: 173 nTPM
  • hypothalamus: 165 nTPM
  • pons: 159 nTPM
  • thalamus: 156 nTPM
  • midbrain: 151 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)
0.92
gnomAD pLI
0.08
gnomAD missense Z
0.77
DepMap mean gene effect
-1.07
DepMap dependency class
common

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 7% 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

  • Sin3 associated polypeptide p18
  • Histone deacetylase complex subunit SAP18
  • Sin3 associated polypeptide p18 superfamily
  • Sin3 associated polypeptide p18 (SAP18)

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of SAP18 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 SAP18 as an antibody target. Whether an autoantibody or antibody against SAP18 could matter depends on whether native SAP18 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

SAP18 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 SAP18 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/SAP18. 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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