Seroatlas · Human Serome Atlas

C9

Complement component C9

Also known as: CO9_HUMAN

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

Protein identityUniProt · HPA

UniProt accession
P02748
Gene
C9
Ensembl
ENSG00000113600
Chromosome
5
Canonical length
559 aa
Protein class
Disease related genes, Human disease related genes, Plasma proteins, Predicted intracellular proteins, Predicted secreted proteins
Secretome location
Secreted to blood
Quaternary structure
Homooligomer

OverviewNCBI Gene

This gene encodes the final component of the complement system. It participates in the formation of the Membrane Attack Complex (MAC). The MAC assembles on bacterial membranes to form a pore, permitting disruption of bacterial membrane organization. Mutations in this gene cause component C9 deficiency. [provided by RefSeq, Feb 2009]

Canonical amino-acid sequenceUniProt

559 residues, UniProt reviewed canonical sequence.

>P02748|C9
     1  MSACRSFAVA ICILEISILT AQYTTSYDPE LTESSGSASH IDCRMSPWSE WSQCDPCLRQ
    61  MFRSRSIEVF GQFNGKRCTD AVGDRRQCVP TEPCEDAEDD CGNDFQCSTG RCIKMRLRCN
   121  GDNDCGDFSD EDDCESEPRP PCRDRVVEES ELARTAGYGI NILGMDPLST PFDNEFYNGL
   181  CNRDRDGNTL TYYRRPWNVA SLIYETKGEK NFRTEHYEEQ IEAFKSIIQE KTSNFNAAIS
   241  LKFTPTETNK AEQCCEETAS SISLHGKGSF RFSYSKNETY QLFLSYSSKK EKMFLHVKGE
   301  IHLGRFVMRN RDVVLTTTFV DDIKALPTTY EKGEYFAFLE TYGTHYSSSG SLGGLYELIY
   361  VLDKASMKRK GVELKDIKRC LGYHLDVSLA FSEISVGAEF NKDDCVKRGE GRAVNITSEN
   421  LIDDVVSLIR GGTRKYAFEL KEKLLRGTVI DVTDFVNWAS SINDAPVLIS QKLSPIYNLV
   481  PVKMKNAHLK KQNLERAIED YINEFSVRKC HTCQNGGTVI LMDGKCLCAC PFKFEGIACE
   541  ISKQKISEGL PALEFPNEK

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against C9 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
3
Mean surface accessibility (rSASA)
0.31
Highest tissue expression
1,223 nTPM

Expression across tissuesHPA

Tissue

  • liver: 1,223 nTPM
  • epididymis: 4.6 nTPM
  • kidney: 0.7 nTPM
  • spleen: 0.4 nTPM
  • testis: 0.4 nTPM
  • adipose tissue: 0.1 nTPM

Single-cell type

  • hepatocytes: 2,517 nCPM
  • medullary thymic epithelial cells: 46 nCPM
  • kupffer cells: 34 nCPM
  • cholangiocytes: 20 nCPM
  • podocytes: 19 nCPM
  • renal collecting duct intercalated cells: 15 nCPM

Immune cell

  • basophil: 0 nTPM
  • classical monocyte: 0 nTPM
  • eosinophil: 0 nTPM
  • gdT-cell: 0 nTPM
  • intermediate monocyte: 0 nTPM
  • MAIT T-cell: 0 nTPM

Brain region

  • choroid plexus: 0.2 nTPM
  • hypothalamus: 0.1 nTPM
  • medulla oblongata: 0.1 nTPM
  • midbrain: 0.1 nTPM
  • pons: 0.1 nTPM
  • thalamus: 0.1 nTPM

DiseaseUniProt · ClinVar · IEDB · PubMed

Four sources answering four different questions about C9.

Disease | AllUniProt

Conditions C9 is implicated in, by any mechanism.

  • Complement component 9 deficiency (C9D) MIM:613825
  • Macular degeneration, age-related, 15 (ARMD15) MIM:615591

Disease | GeneticClinVar

47 pathogenic / likely-pathogenic of 429 ClinVar records.

Conditions with pathogenic or likely-pathogenic variants.

Disease | ImmuneIEDB

Conditions an epitope on C9 was assayed in.

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)
1.51
gnomAD pLI
0
gnomAD missense Z
-0.59
DepMap mean gene effect
-0.06
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

Cellular components

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads C9 as an antibody target. Whether an autoantibody or antibody against C9 could matter depends on whether native C9 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

C9 is annotated at the cell surface, where native C9 is exposed to circulating antibodies and is a prime autoantibody target that could block, deplete, or overstimulate it.

Annotation status

The present source text does not explicitly label C9 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/C9. 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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