<P> Keratin ( / ˈkɛrətɪn / ) 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 . </P>
<P> Keratin ( / ˈkɛrətɪn / ) 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 . </P>
what is the role of keratin in the skin
what is the role of keratin in the skin
outer layer
outer layer