This is an important protein compound that skin, hooves, horns, claws, fur, skin, hair, and nails are all made out of. Aside from forming a multitude of our physical features, keratin also plays a wide variety of roles within the body such as regenerative healing, cell growth, cell signaling, and apoptosis (cell death). Originally, all keratin was thought to be the same type of protein, but scientists have since discovered there are actually 54 different genetic expressions for humans alone.
Although there are many different forms, each keratin falls into two basic types:
According to a 2008 study, nearly half of all of keratins reside in the hair follicles. These proteins play a crucial role during the formation and maturation of the hair itself during all three stages of growth.
The epidermis (the outermost layer of the skin) is made of deadened keratinocytes, which are epithelial cells that have been assigned a specialized task. These specialized cells travel upwards from the lower levels of the skin until they form the epidermis.