Natural fiber Keratin is a structural protein located at the hard surfaces in many vertebrates. Keratin has two forms, α-keratin and β-keratin and are used by different classes of animals. The naming convention for proteins follows that for keratin, alpha keratin is helical and beta keratin is sheet like. Alpha keratin is found in mammalian hair, skin, nails, horn and quills, while beta keratin can be found in avian and reptilian species in scales, feathers, and beaks. The two different structures of keratin have dissimilar mechanical properties, as seen in their dissimilar applications. The relative alignment of the keratin fibrils has a
Leg hair of the hormone testosterone in males that most females have a lower level of. Fibroblast growth factor 5 (FGF5) is a secreted signaling protein. The expression of this protein is detected in hair follicles from the mice that scientists have experimented on. The hair follicles are localized to the outer root sheath during one of the phases of the hair growth cycle. Such experiments conclude that the protein FGF5 functions as an inhibitor when pertaining to hair elongation. Seasonal changes are also known to affect hair growth. For instance, one experiment had concluded that the rate of hair growth for