Keratin 20

Keratin 20, type I
Identifiers
Symbols	KRT20 ; CD20; CK-20; CK20; K20; KRT21
External IDs	OMIM: 608218 MGI: 1914059 HomoloGene: 56837 GeneCards: KRT20 Gene
Gene ontology Molecular function • structural constituent of cytoskeleton • protein binding Cellular component • cytoplasm • intermediate filament Biological process • apoptotic process • cellular response to stress • intermediate filament organization • regulation of protein secretion Sources: Amigo / QuickGO
Orthologs
Species	Human	Mouse
Entrez	54474	66809
Ensembl	ENSG00000171431	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: 99.43 – 99.44 Mb
PubMed search	[1]	[2]

Keratin 20, often abbreviated CK20, is a protein that in humans is encoded by the KRT20 gene.

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.

In immunohistochemistry, antibodies to CK20 can be used to identify a range of adenocarcinomata 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.

Micrograph showing CK20 immunostaining of normal small intestine.