Cytokeratins are proteins that are involved in the cytoskeleton. The cytokeratin proteins are heterotetramers composed of two type I and two type II subunits. Cytokeratin 17 is a type I protein and cytokeratin 7 is a type II intermediate filament protein, each protein contains three coiled-coil domains. Cytokeratin 7 has an approximate molecular weight of 54 kD; cytokeratin 17 has an approximate molecular weight of 46 kD. Cytokeratin 17 is expressed in the basal cells of complex epithelia, but not in stratified or simple epithelia. Cytokeratin 7 is expressed in the epidermis, bronchus, and mesothelium but not in the colon, exocervix or liver. Mutations in cytokeratin 17 have been shown to result in pachyonychia congenital. Cytokeratin 17 has been shown to interact with the EGF receptor. Cytokeratin 7 has been shown to interact with the EGF receptor and heat shock protein 70 kD1A. The C-46 monoclonal antibody recognizes human, bovine and porcine (but not mouse, rat, or rabbit) cytokeratin 7 and cytokeratin 17 and is useful for Western blotting.This antibody has also been reported to be useful for immunoprecipitation, immunohistochemistry (paraffin sections), and immunocytochemistry.