Seroatlas · Human Serome Atlas

RPS21

Small ribosomal subunit protein eS21

Also known as: RS21_HUMAN, S21

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

Protein identityUniProt · HPA

UniProt accession
P63220
Gene
RPS21
Ensembl
ENSG00000171858
Chromosome
20
Canonical length
83 aa
Protein class
Plasma proteins, Predicted intracellular proteins, Ribosomal proteins
Subcellular location
Endoplasmic reticulum,Cytosol

OverviewNCBI Gene

Ribosomes, the organelles that catalyze protein synthesis, consist of a small 40S subunit and a large 60S subunit. Together these subunits are composed of 4 RNA species and approximately 80 structurally distinct proteins. This gene encodes a ribosomal protein that is a component of the 40S subunit. The protein belongs to the S21E family of ribosomal proteins. It is located in the cytoplasm. Alternative splice variants that encode different protein isoforms have been described, but their existence has not been verified. As is typical for genes encoding ribosomal proteins, there are multiple processed pseudogenes of this gene dispersed through the genome. [provided by RefSeq, Jul 2008]

Canonical amino-acid sequenceUniProt

83 residues, UniProt reviewed canonical sequence.

>P63220|RPS21
     1  MQNDAGEFVD LYVPRKCSAS NRIIGAKDHA SIQMNVAEVD KVTGRFNGQF KTYAICGAIR
    61  RMGESDDSIL RLAKADGIVS KNF

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against RPS21 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)
0.41
Highest tissue expression
2,844 nTPM

Expression across tissuesHPA

Tissue

  • ovary: 2,844 nTPM
  • skin: 2,581 nTPM
  • bone marrow: 2,251 nTPM
  • pancreas: 2,166 nTPM
  • skeletal muscle: 1,922 nTPM
  • esophagus: 1,829 nTPM

Single-cell type

  • gastric progenitor cells: 5,381 nCPM
  • breast secretory cells: 4,969 nCPM
  • enteric stem cells: 4,126 nCPM
  • esophageal suprabasal cells: 3,939 nCPM
  • enteric transient amplifying cells: 3,901 nCPM
  • gastric chief cells: 3,769 nCPM

Immune cell

  • total PBMC: 3,117 nTPM
  • memory B-cell: 2,705 nTPM
  • naive CD4 T-cell: 2,659 nTPM
  • naive B-cell: 2,544 nTPM
  • naive CD8 T-cell: 2,414 nTPM
  • memory CD4 T-cell: 2,251 nTPM

Brain region

  • thalamus: 473 nTPM
  • white matter: 457 nTPM
  • basal ganglia: 433 nTPM
  • cerebral cortex: 428 nTPM
  • spinal cord: 412 nTPM
  • amygdala: 368 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)
1.09
gnomAD pLI
0.14
gnomAD missense Z
1.16
DepMap mean gene effect
-1.63
DepMap dependency class
pan

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 9% 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

  • Small ribosomal subunit protein eS21
  • Small ribosomal subunit protein eS21, conserved site
  • Small ribosomal subunit protein eS21 superfamily
  • Ribosomal protein S21e

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of RPS21 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 RPS21 as an antibody target. Whether an autoantibody or antibody against RPS21 could matter depends on whether native RPS21 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

RPS21 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 RPS21 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/RPS21. 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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