Keratin 20

Keratin 20, often abbreviated CK20, is a protein that in humans is encoded by the KRT20 gene.^[5][6][7]

KRT20
Identifiers
Aliases	KRT20, CD20, CK-20, CK20, K20, KRT21, keratin 20
External IDs	OMIM: 608218; MGI: 1914059; HomoloGene: 56837; GeneCards: KRT20; OMA:KRT20 - orthologs
Gene location (Human) Chr. Chromosome 17 (human)[1] Band 17q21.2 Start 40,875,889 bp[1] End 40,885,242 bp[1]
Gene location (Mouse) Chr. Chromosome 11 (mouse)[2] Band 11|11 D Start 99,319,229 bp[2] End 99,328,976 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in mucosa of transverse colon rectum duodenum appendix epithelium of colon gastric mucosa smooth muscle tissue body of stomach urinary bladder muscle layer of sigmoid colon Top expressed in intestinal villus Ileal epithelium large intestine colon duodenum left colon mucous cell of stomach pyloric antrum Paneth cell jejunum More reference expression data BioGPS n/a
Gene ontology Molecular function structural molecule activity protein binding structural constituent of cytoskeleton Cellular component cytoplasm intermediate filament cytosol Biological process intermediate filament organization apoptotic process regulation of protein secretion keratinization cornification cellular response to starvation Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 54474 66809 Ensembl ENSG00000171431 ENSG00000263057 ENSMUSG00000035775 UniProt P35900 Q9D312 RefSeq (mRNA) NM_019010 NM_023256 RefSeq (protein) NP_061883 NP_075745 Location (UCSC) Chr 17: 40.88 – 40.89 Mb Chr 11: 99.32 – 99.33 Mb PubMed search [3] [4]
Wikidata
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Keratin 20 is a type I cytokeratin. It is a major cellular protein of mature enterocytes and goblet cells and is specifically found in the gastric and intestinal mucosa.^[8]

In immunohistochemistry, antibodies to CK20 can be used to identify a range of adenocarcinoma arising from epithelia that normally contain the CK20 protein. For example, the protein is commonly found in colorectal cancer, transitional cell carcinomas and in Merkel cell carcinoma, but is absent in lung cancer, prostate cancer, and non-mucinous ovarian cancer. It is often used in combination with antibodies to CK7 to distinguish different types of glandular tumour.^[9]

Micrograph showing CK20 immunostaining of normal small intestine.

CK7 and CK20 expression by various body locations.^[10]