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 '
Vitelline membrane outer layer protein I (VMO-I) Vitelline membrane outer layer protein I (VMO-I) In molecular biology, this entry refers to a protein domain called, the Vitelline membrane outer layer protein I (VMO-I). It is a structure found on the outside of an egg, in the vitelline membrane. The major role of the vitelline membrane is to prevent the mixing of the yolk and albumen and also act as an important anti-microbial barrier, as indicated by the high content of lysozyme in the outer layer Vitelline membrane outer layer protein I (VMO-I) binds tightly to ovomucin fibrils, which construct the backbone of the outer layer membrane. VMO-I