Seroatlas · Human Serome Atlas

CDKN1A

Cyclin-dependent kinase inhibitor 1

Also known as: CAP20, CDKN1, CDN1A_HUMAN, CIP1, P21, p21CIP1, p21Cip1/Waf1, SDI1, WAF1

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

Protein identityUniProt · HPA

UniProt accession
P38936
Gene
CDKN1A
Ensembl
ENSG00000124762
Chromosome
6
Canonical length
164 aa
Protein class
Cancer-related genes, Human disease related genes, Predicted intracellular proteins
Subcellular location
Nucleoplasm,Nuclear bodies

OverviewNCBI Gene

This gene encodes a potent cyclin-dependent kinase inhibitor. The encoded protein binds to and inhibits the activity of cyclin-cyclin-dependent kinase2 or -cyclin-dependent kinase4 complexes, and thus functions as a regulator of cell cycle progression at G1. The expression of this gene is tightly controlled by the tumor suppressor protein p53, through which this protein mediates the p53-dependent cell cycle G1 phase arrest in response to a variety of stress stimuli. This protein can interact with proliferating cell nuclear antigen, a DNA polymerase accessory factor, and plays a regulatory role in S phase DNA replication and DNA damage repair. This protein was reported to be specifically cleaved by CASP3-like caspases, which thus leads to a dramatic activation of cyclin-dependent kinase2, and may be instrumental in the execution of apoptosis following caspase activation. Mice that lack this gene have the ability to regenerate damaged or missing tissue. Multiple alternatively spliced variants have been found for this gene. [provided by RefSeq, Sep 2015]

Canonical amino-acid sequenceUniProt

164 residues, UniProt reviewed canonical sequence.

>P38936|CDKN1A
     1  MSEPAGDVRQ NPCGSKACRR LFGPVDSEQL SRDCDALMAG CIQEARERWN FDFVTETPLE
    61  GDFAWERVRG LGLPKLYLPT GPRRGRDELG GGRRPGTSPA LLQGTAEEDH VDLSLSCTLV
   121  PRSGEQAEGS PGGPGDSQGR KRRQTSMTDF YHSKRRLIFS KRKP

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against CDKN1A 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)
0.65
Highest tissue expression
340 nTPM

Expression across tissuesHPA

Tissue

  • blood vessel: 340 nTPM
  • adipose tissue: 316 nTPM
  • choroid plexus: 301 nTPM
  • skeletal muscle: 236 nTPM
  • skin: 222 nTPM
  • esophagus: 202 nTPM

Single-cell type

  • epididymal basal cells: 861 nCPM
  • ocular epithelial cells: 839 nCPM
  • urothelial cells: 765 nCPM
  • vascular smooth muscle cells: 707 nCPM
  • esophageal apical cells: 585 nCPM
  • esophageal suprabasal cells: 572 nCPM

Immune cell

  • non-classical monocyte: 75 nTPM
  • intermediate monocyte: 52 nTPM
  • total PBMC: 34 nTPM
  • classical monocyte: 23 nTPM
  • plasmacytoid DC: 22 nTPM
  • memory B-cell: 21 nTPM

Brain region

  • choroid plexus: 106 nTPM
  • medulla oblongata: 59 nTPM
  • midbrain: 44 nTPM
  • spinal cord: 43 nTPM
  • white matter: 39 nTPM
  • pons: 39 nTPM

DiseaseUniProt · ClinVar · IEDB · PubMed

Four sources answering four different questions about CDKN1A.

Disease | GeneticClinVar

1 pathogenic / likely-pathogenic of 47 ClinVar records.

Conditions with pathogenic or likely-pathogenic variants.

Disease | ImmuneIEDB

Conditions an epitope on CDKN1A 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)
1.38
gnomAD pLI
0
gnomAD missense Z
0.42
DepMap mean gene effect
0.29
DepMap dependency class
none

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

Molecular functions

Cellular components

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of CDKN1A 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 CDKN1A as an antibody target. Whether an autoantibody or antibody against CDKN1A could matter depends on whether native CDKN1A is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

CDKN1A 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 CDKN1A as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/CDKN1A. 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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