Seroatlas · Human Serome Atlas

C18orf21

UPF0711 protein C18orf21

Also known as: CR021_HUMAN, HsT3108, PNAS-124, PNAS-131

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

Protein identityUniProt · HPA

UniProt accession
Q32NC0
Gene
C18orf21
Ensembl
ENSG00000141428
Chromosome
18
Canonical length
220 aa
Protein class
Predicted intracellular proteins
Subcellular location
Nucleoli,Plasma membrane

OverviewNCBI Gene

No narrative summary is available for C18orf21 in this catalog release; identity and structured annotations are shown without generated factual claims.

Canonical amino-acid sequenceUniProt

220 residues, UniProt reviewed canonical sequence.

>Q32NC0|C18orf21
     1  MRQKHYLEAA ARGLHDSCPG QARYLLWAYT SSHDDKSTFE ETCPYCFQLL VLDNSRVRLK
    61  PKARLTPKIQ KLLNREARNY TLSFKEAKMV KKFKDSKSVL LITCKTCNRT VKHHGKSRSF
   121  VSTLKSNPAT PTSKLSLKTP ERRTANPNHD MSGSKGKSPA SVFRTPTSGQ SVSTCSSKNT
   181  SKTKKHFSQL KMLLSQNESQ KIPKVDFRNF LSSLKGGLLK

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against C18orf21 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
Intracellular
Secreted
No
Transmembrane segments
0
Mean surface accessibility (rSASA)
0.51
Highest tissue expression
68 nTPM

Expression across tissuesHPA

Tissue

  • bone marrow: 68 nTPM
  • testis: 33 nTPM
  • skeletal muscle: 33 nTPM
  • tongue: 25 nTPM
  • pancreas: 23 nTPM
  • thymus: 20 nTPM

Single-cell type

  • late primary spermatocytes: 271 nCPM
  • early spermatids: 116 nCPM
  • late spermatids: 85 nCPM
  • oocytes: 60 nCPM
  • early primary spermatocytes: 57 nCPM
  • epididymal clear cells: 47 nCPM

Immune cell

  • basophil: 98 nTPM
  • T-reg: 42 nTPM
  • memory B-cell: 35 nTPM
  • eosinophil: 34 nTPM
  • naive B-cell: 31 nTPM
  • intermediate monocyte: 31 nTPM

Brain region

  • cerebellum: 20 nTPM
  • cerebral cortex: 16 nTPM
  • white matter: 15 nTPM
  • spinal cord: 14 nTPM
  • thalamus: 13 nTPM
  • hypothalamus: 13 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)
1.55
gnomAD pLI
0
gnomAD missense Z
0.3
DepMap mean gene effect
-0.53
DepMap dependency class
common

OntologyGO

Biological processes

Cellular components

Protein domainsUniProt · Pfam · InterPro

  • Ribonuclease MRP subunit P24-like
  • Ribonuclease MRP subunit P24-like

KeywordsUniProt

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads C18orf21 as an antibody target. Whether an autoantibody or antibody against C18orf21 could matter depends on whether native C18orf21 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

C18orf21 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 C18orf21 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/C18orf21. 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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