Cytokeratin 17: Proteins and Enzymes

Among the members of the cytokeratin (CK) subfamily of intermediate filament (IF) proteins, CK 17 is normally expressed in the basal cells of complex epithelia but not in stratified or simple epithelia. It has an unusual expression pattern in normal and diseased states and has potential importance in tumor diagnosis. CK 17 synthesis seems to be a marker of basal cell differentiation in complex epithelia and therefore indicative of a certain type of epithelial "stem cells" (1). It has been shown that CK 17 regulates cell growth through binding to the adaptor protein 14-3-3sigma. These findings reveal a new and unexpected role for the intermediate filament cytoskeleton in influencing cell growth and size by regulating protein synthesis (2). CK 17 is expressed in the nail bed, hair follicle, sebaceous glands, and other epidermal appendages (3).