Which protein allows the skin to stretch and recoil?

The correct answer is elastin. Elastin is a vital protein in the extracellular matrix of connective tissues that provides elasticity and resilience. This means it allows the skin and other tissues to stretch and then return to their original shape, similar to how a rubber band behaves. The ability to stretch and recoil is essential for maintaining the skin's structural integrity, which is particularly important in areas that undergo frequent deformation, such as the skin on the body or around joints.

While keratin is a structural protein that provides strength and protection to the skin, nails, and hair, it does not contribute to elasticity. Collagen, another key structural protein, primarily provides tensile strength and support but lacks the elastic properties found in elastin. Actin is a protein involved in muscle contraction and cellular movement but is not directly associated with the elasticity of the skin. Therefore, the role of elastin is crucial in enabling the skin to stretch and recoil effectively.