Keratin is a protein that forms many different structures including hair, feathers, hooves, the baleen of various whale species, and epithelial cells. Keratinocytes make up 90% of the cells in the upper layers of human skin or epidermis. Approximately 30 families of keratin are found in the human body, and 54 genes are related to keratin and its functions.


1. Keratin Types

Keratin can be malleable or stiff. There are two types of the protein: alpha-keratins or beta-keratins. The type of keratin is determined by the structure and hydrogen or sulfide bonds forming the protein. Alpha-keratins are the most common type in mammals, forming hair, skin, and wool. Beta-keratins are common in birds and reptiles. The hard shells or overlapping plates of animals such as armadillos and turtles usually contain both types of keratin.

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