What skin protein prevents water loss?

The correct answer is: Keratin

The skin is the body's largest organ and protects it from the elements. Keratin is a type of protein that forms the outermost layer of the skin, called the epidermis. Keratinocytes, the cells that make up the epidermis, produce keratin as they move towards the skin's surface where they eventually die and form a protective layer that prevents water loss and harmful substances from entering the body. Additionally, keratin also provides strength and flexibility to the skin, protects against UV radiation, and helps maintain skin moisture. Other examples of other proteins important for skin health include collagen and elastin which provide strength and elasticity.