Fibril and hence the whole muscle. Elastin is a fibrous protein common in various soft tissues, like skin, blood vessels and lung tissue. Each monomer connects with each other, forming a 3D network, with ability to endure over 200% strain before deformation. Keratin is a structural protein mainly found in hair, nails, hooves, horns, quills. Basically keratin is formed by polypeptide chains, which coil into α-helices with sulfur cross-links or bond into β-sheets linked by hydrogen bonding. β-keratin, which is tougher than α-conformation, is more common in birds and reptiles. Resilin is an elastomeric insect protein, consisting of both α-helices and
Protein domain Pfam database using the prefix DUF followed by a number, with examples being DUF2992 and DUF1220. There are now over 3,000 DUF families within the Pfam database representing over 20% of known families. "This article incorporates text and figures from George, R. A. (2002) "Predicting Structural Domains in Proteins" Thesis, University College London, which were contributed by its author." Protein domain A protein domain is a conserved part of a given protein sequence and (tertiary) structure that can evolve, function, and exist independently of the rest of the protein chain. Each domain forms a compact three-dimensional structure and often can