Keratin Keratin Keratin () is one of a family of fibrous structural proteins. It is the key structural material making up hair, horns, claws, hooves, and the outer layer of human skin. Keratin is also the protein that protects epithelial cells from damage or stress. Keratin is extremely insoluble in water and organic solvents. Keratin monomers assemble into bundles to form intermediate filaments, which are tough and form strong unmineralized epidermal appendages found in reptiles, birds, amphibians, and mammals. The only other biological matter known to approximate the toughness of keratinized tissue is chitin. Keratin derives from Greek ' from '
Keratin 6A encoded by separate genes located within the type II keratin gene cluster on human chromosome 12q. It is found with keratin 16 and/or keratin 17 in the palm and sole epidermis, the epithelial cells of the nail bed, the filiform papillae of the tongue, the epithelial lining of oral mucosa and esophagus, as well as the hair follicles. This keratin 6 isoform is thought to be the most abundant of the K6 isoforms. The "KRT6A" gene consists of 9 exons separated by 8 introns and is located in the type II keratin gene cluster on human "chromosome" 12q. Keratin 6B