Seroatlas · Human Serome Atlas

SAA1

Serum amyloid A-1 protein

Also known as: PIG4, SAA, SAA1_HUMAN, TP53I4

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

Protein identityUniProt · HPA

UniProt accession
P0DJI8
Gene
SAA1
Ensembl
ENSG00000173432
Chromosome
11
Canonical length
122 aa
Protein class
Disease related genes, Predicted secreted proteins
Secretome location
Secreted to blood
Quaternary structure
Homohexamer

OverviewNCBI Gene

This gene encodes a member of the serum amyloid A family of apolipoproteins. The encoded preproprotein is proteolytically processed to generate the mature protein. This protein is a major acute phase protein that is highly expressed in response to inflammation and tissue injury. This protein also plays an important role in HDL metabolism and cholesterol homeostasis. High levels of this protein are associated with chronic inflammatory diseases including atherosclerosis, rheumatoid arthritis, Alzheimer's disease and Crohn's disease. This protein may also be a potential biomarker for certain tumors. Finally, antimicrobial activity against S. aureus and E. coli resides in the N-terminal portion of the mature protein. Alternate splicing results in multiple transcript variants that encode the same protein. A pseudogene of this gene is found on chromosome 11. [provided by RefSeq, Jul 2020]

Canonical amino-acid sequenceUniProt

122 residues, UniProt reviewed canonical sequence.

>P0DJI8|SAA1
     1  MKLLTGLVFC SLVLGVSSRS FFSFLGEAFD GARDMWRAYS DMREANYIGS DKYFHARGNY
    61  DAAKRGPGGA WAAEVITDAR ENIQRFFGHG AEDSLADQAA NEWGRSGKDP NHFRPAGLPE
   121  KY

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against SAA1 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)
0.34
Highest tissue expression
54,033 nTPM

Expression across tissuesHPA

Tissue

  • liver: 54,033 nTPM
  • salivary gland: 2,841 nTPM
  • adipose tissue: 2,324 nTPM
  • breast: 1,727 nTPM
  • skeletal muscle: 567 nTPM
  • cervix: 246 nTPM

Single-cell type

  • hepatocytes: 25,740 nCPM
  • thymic myoid cells: 1,978 nCPM
  • salivary acinar cells: 1,606 nCPM
  • lacrimal acinar cells: 1,344 nCPM
  • breast myoepithelial cells: 1,319 nCPM
  • salivary myoepithelial cells: 1,245 nCPM

Immune cell

  • intermediate monocyte: 0.3 nTPM
  • memory B-cell: 0.3 nTPM
  • gdT-cell: 0.1 nTPM
  • basophil: 0 nTPM
  • classical monocyte: 0 nTPM
  • eosinophil: 0 nTPM

Brain region

  • thalamus: 14 nTPM
  • pons: 8.3 nTPM
  • choroid plexus: 3.7 nTPM
  • medulla oblongata: 1.7 nTPM
  • midbrain: 1.7 nTPM
  • hippocampal formation: 0.6 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)
1.61
gnomAD pLI
0.01
gnomAD missense Z
0.02

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 2% 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 SAA1 as an antibody target. Whether an autoantibody or antibody against SAA1 could matter depends on whether native SAA1 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

SAA1 is annotated as secreted, so native SAA1 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 SAA1 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/SAA1. 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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