Seroatlas · Human Serome Atlas

C1QTNF9B

Complement C1q and tumor necrosis factor-related protein 9B

Also known as: C1T9B_HUMAN, CTRP9B

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

Protein identityUniProt · HPA

UniProt accession
B2RNN3
Gene
C1QTNF9B
Ensembl
ENSG00000205863
Chromosome
13
Canonical length
333 aa
Protein class
Predicted secreted proteins
Secretome location
Secreted - unknown location

OverviewNCBI Gene

Predicted to enable hormone activity and identical protein binding activity. Predicted to act upstream of or within several processes, including negative regulation of cell size; positive regulation of cellular response to insulin stimulus; and positive regulation of protein serine/threonine kinase activity. Predicted to be located in extracellular space. Predicted to be part of collagen trimer. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

333 residues, UniProt reviewed canonical sequence.

>B2RNN3|C1QTNF9B
     1  MRIWWLLLAI EICTGNINSQ DTCRQGHPGI PGNPGHNGLP GRDGRDGAKG DKGDAGEPGC
    61  PGSPGKDGTS GEKGERGADG KVEAKGIKGD QGSRGSPGKH GPKGLAGPMG EKGLRGETGP
   121  QGQKGNKGDV GPTGPEGPRG NIGPLGPTGL PGPMGPIGKP GPKGEAGPTG PQGEPGVRGI
   181  RGWKGDRGEK GKIGETLVLP KSAFTVGLTV LSKFPSSDVP IKFDKILYNE FNHYDTAVGK
   241  FTCHIAGVYY FTYHITVFSR NVQVSLVKNG VKILHTRDAY VSSEDQASGS IVLQLKLGDE
   301  MWLQVTGGER FNGLFADEDD DTTFTGFLLF SSQ

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against C1QTNF9B 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)
0.55
Highest tissue expression
17 nTPM

Expression across tissuesHPA

Tissue

  • skin: 17 nTPM
  • hippocampal formation: 9.5 nTPM
  • testis: 8.3 nTPM
  • prostate: 4 nTPM
  • skeletal muscle: 3.8 nTPM
  • heart muscle: 3.3 nTPM

Single-cell type

  • undifferentiated spermatogonia: 3.6 nCPM
  • cardiomyocytes: 3.3 nCPM
  • late spermatids: 3.2 nCPM
  • brain excitatory neurons: 2.4 nCPM
  • early spermatids: 1.9 nCPM
  • late primary spermatocytes: 0.9 nCPM

Immune cell

  • plasmacytoid DC: 0.7 nTPM
  • naive B-cell: 0.5 nTPM
  • eosinophil: 0.4 nTPM
  • NK-cell: 0.4 nTPM
  • non-classical monocyte: 0.4 nTPM
  • gdT-cell: 0.3 nTPM

Brain region

  • hippocampal formation: 17 nTPM
  • hypothalamus: 4.1 nTPM
  • cerebral cortex: 2.4 nTPM
  • amygdala: 2.3 nTPM
  • basal ganglia: 2 nTPM
  • midbrain: 1.4 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)
1.5
gnomAD pLI
0
gnomAD missense Z
0.18
DepMap mean gene effect
-0.22
DepMap dependency class
selective

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

Cellular components

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of C1QTNF9B 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 C1QTNF9B as an antibody target. Whether an autoantibody or antibody against C1QTNF9B could matter depends on whether native C1QTNF9B is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

C1QTNF9B is annotated as secreted, so native C1QTNF9B 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 C1QTNF9B as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/C1QTNF9B. 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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