Alternative titles; symbols
HGNC Approved Gene Symbol: KRT20
Cytogenetic location: 17q21.2 Genomic coordinates (GRCh38) : 17:40,875,889-40,885,242 (from NCBI)
KRT20 is an integral intermediate filament component and is a major cytoskeletal keratin of the intestinal epithelium (Moll et al., 1990).
Moll et al. (1990) purified KRT20, which they designated protein IT, from human intestinal mucosa and from cytoskeletal intermediate filaments. KRT20 has an apparent molecular mass of about 46 kD. Antibodies raised against KRT20 decorated typical cytokeratin fibril arrays in normal and transformed intestinal cells. Immunocytochemical analysis of several human and rat tissues showed that KRT20 is a prominent component of intestinal and gastric foveolar epithelium, urothelial umbrella cells, and Merkel cells of epidermis. Sparse positive epithelial cells were noted in the thymus, bronchus, gallbladder, and prostate gland.
Using rat Krt21 as probe, Calnek and Quaroni (1993) obtained a partial cDNA encoding KRT20, which they called CK20, from a colon tumor cell line cDNA library. The partial sequence, extending from the end of coil-1a of the alpha-helical rod domain to the polyadenylation tail region, contains a highly conserved consensus sequence typically found in the coil-1b alpha-helical rod domain of type I keratins. The partial KRT20 protein shares 83% amino acid identity with the comparable sequence of rat Krt21, which the authors renamed Ck20, or Krt20, to reflect its homology with the human protein. The human and rat proteins share 86% amino acid identity in the C-terminal nonhelical extension. In situ hybridization of rat intestine detected expression of Krt20 only after 20 days gestation (2 days before birth), when the intestinal epithelium contained terminally differentiated epithelial cells; Krt20 was expressed with Krt8 (148060) by the entire epithelium.
Moll et al. (1990) found that KRT20 formed heterotypic complexes with KRT8 in vitro, and the complexes assembled into intermediate filaments under appropriate conditions.
By genomic sequence analysis, Rogers et al. (2001) mapped the KRT20 gene to the keratin gene cluster on chromosome 17q12-q21, which contains KRT12 (601687) and several type I hair keratin genes (see 601077).
Calnek, D., Quaroni, A. Differential localization by in situ hybridization of distinct keratin mRNA species during intestinal epithelial cell development and differentiation. Differentiation 53: 95-104, 1993. [PubMed: 7689500] [Full Text: https://doi.org/10.1111/j.1432-0436.1993.tb00649.x]
Moll, R., Schiller, D. L., Franke, W. W. Identification of protein IT of the intestinal cytoskeleton as a novel type I cytokeratin with unusual properties and expression patterns. J. Cell Biol. 111: 567-580, 1990. [PubMed: 1696264] [Full Text: https://doi.org/10.1083/jcb.111.2.567]
Rogers, M. A., Langbein, L., Winter, H., Ehmann, C., Praetzel, S., Korn, B., Schweizer, J. Characterization of a cluster of human high/ultrahigh sulfur keratin-associated protein genes embedded in the type I keratin gene domain on chromosome 17q12-21. J. Biol. Chem. 276: 19440-19451, 2001. [PubMed: 11279113] [Full Text: https://doi.org/10.1074/jbc.M100657200]