Keratin 7

Function

Keratin-7 is a member of the keratin gene family. The type II cytokeratins consist of basic or neutral proteins which are arranged in pairs of heterotypic keratin chains coexpressed during differentiation of simple and stratified epithelial tissues. This type II cytokeratin is specifically expressed in the simple epithelia lining the cavities of the internal organs and in the gland ducts and blood vessels. The genes encoding the type II cytokeratins are clustered in a region of chromosome 12q12-q13. Alternative splicing may result in several transcript variants; however, not all variants have been fully described.

Keratin-7 is found in simple glandular epithelia, and in transitional epithelium. Epithelial cells of the lung and breast both contain keratin-7, but some other glandular epithelia, such as those of the colon and prostate, do not.

Immunohistochemistry

Because the keratin-7 antigen is found in both healthy and neoplastic cells, antibodies to CK7 can be used in immunohistochemistry to distinguish ovarian and transitional cell carcinomas (staining positive) from colonic and prostate cancers (negative), respectively. It is commonly used together with CK20 when making such diagnoses.

Mikael Häggström, MD. More info at image description page in Wikimedia Commons.]]

References

References

1. (Aug 1991). "Three epidermal and one simple epithelial type II keratin genes map to human chromosome 12". Cytogenetics and Cell Genetics.
2. (Jul 2006). "New consensus nomenclature for mammalian keratins". The Journal of Cell Biology.
3. "Entrez Gene: KRT7 keratin 7".
4. Leong, Anthony S-Y. (2003). "Manual of Diagnostic Cytology". Greenwich Medical Media, Ltd..