Seroatlas · Human Serome Atlas

C1orf21

Uncharacterized protein C1orf21

Also known as: CA021_HUMAN, PIG13

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

Protein identityUniProt · HPA

UniProt accession
Q9H246
Gene
C1orf21
Ensembl
ENSG00000116667
Chromosome
1
Canonical length
121 aa
Protein class
Predicted intracellular proteins
Subcellular location
Nucleoplasm,Cytosol

OverviewNCBI Gene

No narrative summary is available for C1orf21 in this catalog release; identity and structured annotations are shown without generated factual claims.

Canonical amino-acid sequenceUniProt

121 residues, UniProt reviewed canonical sequence.

>Q9H246|C1orf21
     1  MGCASAKHVA TVQNEEEAQK GKNYQNGDVF GDEYRIKPVE EVKYMKNGAE EEQKIAARNQ
    61  ENLEKSASSN VRLKTNKEVP GLVHQPRANM HISESQQEFF RMLDEKIEKG RDYCSEEEDI
   121  T

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against C1orf21 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
Unknown
Secreted
No
Transmembrane segments
0
Mean surface accessibility (rSASA)
0.65
Highest tissue expression
36 nTPM

Expression across tissuesHPA

Tissue

  • skeletal muscle: 36 nTPM
  • tongue: 19 nTPM
  • cerebral cortex: 18 nTPM
  • cerebellum: 15 nTPM
  • amygdala: 14 nTPM
  • skin: 13 nTPM

Single-cell type

  • myonuclei: 1,766 nCPM
  • pituicytes/fscs: 727 nCPM
  • basal prostatic cells: 618 nCPM
  • syncytiotrophoblasts: 616 nCPM
  • fibro-adipogenic progenitors: 534 nCPM
  • oligodendrocyte progenitor cells: 530 nCPM

Immune cell

  • gdT-cell: 3.9 nTPM
  • NK-cell: 2.6 nTPM
  • memory CD8 T-cell: 2 nTPM
  • naive CD8 T-cell: 1.8 nTPM
  • total PBMC: 0.9 nTPM
  • memory CD4 T-cell: 0.5 nTPM

Brain region

  • cerebral cortex: 37 nTPM
  • basal ganglia: 36 nTPM
  • hippocampal formation: 32 nTPM
  • cerebellum: 29 nTPM
  • pons: 28 nTPM
  • medulla oblongata: 27 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)
0.41
gnomAD pLI
0.89
gnomAD missense Z
0.79
DepMap mean gene effect
0
DepMap dependency class
none

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).

Protein domainsUniProt · Pfam · InterPro

  • Protein of unknown function DUF4612
  • Domain of unknown function (DUF4612)

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of C1orf21 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 C1orf21 as an antibody target. Whether an autoantibody or antibody against C1orf21 could matter depends on whether native C1orf21 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

C1orf21 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 C1orf21 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/C1orf21. 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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