Keratin, collagen, elastin and fibronectin are some examples of fibrous proteins. Fibrous proteins contain repeating sets of amino acid residues that make them both strong and elongated. They are insoluble and carry out important tasks in the body.
Collagen is the most abundant fibrous protein in the human body. A typical collagen molecule contains three polypeptide chains joined together by hydrogen bonds in the chain. Collagen is mostly found in the bones, skin and connective tissues within the body. It provides structural strength, support and a degree of elasticity to the body tissues.
Keratin has a seven amino acid repeating structure. There are more than twenty-five variations of keratin in the cells of mammals. In humans, keratin is mostly found in hair and nails while in animals it is found in feathers, wool and horns. Keratin provides strength to the body tissues.
Elastin gives connective tissues and organs rigidity, so that they can stretch, recoil and return to their original state. It also plays a vital role in maintaining and supporting healthy cells. Fibronectin molecule has a rod like structure in which three polypeptides are wound around each other. Fibronectin is involved in many cellular processes, including cell migration/adhesion, blood clotting, embryogenesis and tissue repair.