Which of the following proteins is a constituent of nails, hair and feathers?
The correct option is D
Keratin a fibrous protein forming the main structural constituent of hair, feathers, hoofs, claws, horns, etc. Collagen is the main structural protein found in skin and other connective tissues. Elastin is a highly elastic protein in connective tissue and allows many tissues in the body to resume their shape after stretching or contracting. Keratan sulfate is a sulphated structural carbohydrate that have been found especially in the cornea, cartilage, and bone. Keratan sulfates are large, highly hydrated molecules which in joints can act as a cushion to absorb mechanical shock.