Which protein is primarily responsible for skin's elasticity and its ability to stretch and recoil?

• A. Elastin
• B. Collagen
• C. Keratin
• D. Melanin

Answer: (A)

Elastin is the protein that gives skin its elasticity by forming an elastic fiber network in the dermis. When the skin stretches, elastin fibers extend, and thanks to their elastic properties and crosslinking (tropoelastin with desmosine and isodesmosine), they recoil to the original length, letting the skin snap back after movement. Collagen supplies tensile strength and structure but isn’t highly elastic, keratin is the tough protein in the epidermis, hair, and nails, and melanin is the pigment that gives color. As we age or with sun exposure, elastin can degrade, reducing elasticity and causing sagging, even though collagen remains important for overall skin support.