Seroatlas · Human Serome Atlas

FCAR

Immunoglobulin alpha Fc receptor

Also known as: CD89, FcalphaR, FcalphaRI, FCAR_HUMAN

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

Protein identityUniProt · HPA

UniProt accession
P24071
Gene
FCAR
Ensembl
ENSG00000186431
Chromosome
19
Canonical length
287 aa
Protein class
CD markers, Predicted intracellular proteins, Predicted membrane proteins
Subcellular location
Plasma membrane
Secretome location
Intracellular and membrane

OverviewNCBI Gene

This gene is a member of the immunoglobulin gene superfamily and encodes a receptor for the Fc region of IgA. The receptor is a transmembrane glycoprotein present on the surface of myeloid lineage cells such as neutrophils, monocytes, macrophages, and eosinophils, where it mediates immunologic responses to pathogens. It interacts with IgA-opsonized targets and triggers several immunologic defense processes, including phagocytosis, antibody-dependent cell-mediated cytotoxicity, and stimulation of the release of inflammatory mediators. Multiple alternatively spliced transcript variants encoding different isoforms have been described for this gene. [provided by RefSeq, Jul 2008]

Canonical amino-acid sequenceUniProt

287 residues, UniProt reviewed canonical sequence.

>P24071|FCAR
     1  MDPKQTTLLC LVLCLGQRIQ AQEGDFPMPF ISAKSSPVIP LDGSVKIQCQ AIREAYLTQL
    61  MIIKNSTYRE IGRRLKFWNE TDPEFVIDHM DANKAGRYQC QYRIGHYRFR YSDTLELVVT
   121  GLYGKPFLSA DRGLVLMPGE NISLTCSSAH IPFDRFSLAK EGELSLPQHQ SGEHPANFSL
   181  GPVDLNVSGI YRCYGWYNRS PYLWSFPSNA LELVVTDSIH QDYTTQNLIR MAVAGLVLVA
   241  LLAILVENWH SHTALNKEAS ADVAEPSWSQ QMCQPGLTFA RTPSVCK

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against FCAR 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
Cell surface
Secreted
No
Transmembrane segments
1
Mean surface accessibility (rSASA)
0.39
Highest tissue expression
25 nTPM

Expression across tissuesHPA

Tissue

  • bone marrow: 25 nTPM
  • spleen: 15 nTPM
  • lung: 11 nTPM
  • adipose tissue: 4.3 nTPM
  • fallopian tube: 2 nTPM
  • liver: 1.8 nTPM

Single-cell type

  • neutrophils: 20 nCPM
  • neutrophil progenitors: 7.3 nCPM
  • monocytes: 6.7 nCPM
  • microglia: 3.1 nCPM
  • macrophages: 0.9 nCPM
  • monocyte progenitors: 0.9 nCPM

Immune cell

  • neutrophil: 4.1 nTPM
  • classical monocyte: 1.3 nTPM
  • total PBMC: 0.4 nTPM
  • intermediate monocyte: 0.3 nTPM
  • basophil: 0 nTPM
  • eosinophil: 0 nTPM

Brain region

  • cerebral cortex: 0.6 nTPM
  • pons: 0.2 nTPM
  • basal ganglia: 0.1 nTPM
  • choroid plexus: 0.1 nTPM
  • medulla oblongata: 0.1 nTPM
  • midbrain: 0.1 nTPM

ReferencesPubMed · IEDB

Publications for FCAR from three distinct lines of evidence, kept separate because they answer different questions: whether antibodies are directed at the protein, whether a B-cell epitope has been mapped on it, and whether a T-cell epitope has. Each is labelled with its source.

Reference: AutoantibodyPubMed

7 publications

Show 2 more

Sources: PubMed — antigen-level antibody evidence from a custom retrieval. Records matching a controlled set of autoantibody terms (the MeSH descriptors Autoantibodies and Autoantigens, with title and abstract term variants) were obtained through NCBI E-utilities, and their titles and abstracts parsed for constructions that direct an antibody at a named protein rather than for co-occurrence. Captured names were resolved against UniProt nomenclature and each antigen adjudicated individually against the source text. Bibliographic records from PubMed and MeSH, U.S. National Library of Medicine; citation metrics from NIH iCite (Hutchins et al., PLoS Biology 2016). Titles link to PubMed; abstracts are not reproduced here. The NLM does not endorse this analysis.

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)
1.63
gnomAD pLI
0
gnomAD missense Z
-0.66
DepMap mean gene effect
0.09
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 FCAR as an antibody target. Whether an autoantibody or antibody against FCAR could matter depends on whether native FCAR is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

FCAR is annotated at the cell surface, where native FCAR is exposed to circulating antibodies and is a prime autoantibody target that could block, deplete, or overstimulate it.

Source-annotated serology context

The source annotations explicitly mention antibody, autoantibody, autoantigen, or autoimmune context. This is biological context, not study-specific reactivity.

  • It interacts with IgA-opsonized targets and triggers several immunologic defense processes, including phagocytosis, antibody-dependent cell-mediated cytotoxicity, and stimulation of the release of inflammatory mediators.

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