Elastin

Elastin, is a protein in connective tissue that is elastic and allows many tissues in the body to resume their shape after stretching or contracting. Elastin helps skin to return to its original position when it is poked or pinched.

Composition
It is primarily composed of the amino acids glycine, valine, alanine, and proline.

Elastin is made by linking many soluble tropoelastin protein molecules, in a reaction catalyzed by lysyl oxidase, to make a massive insoluble, durable cross-linked array.

Desmosine and isodesmosine are both found in elastin.

Locations in body
Elastin serves an important function in arteries and is particularly abundant in large elastic blood vessels such as the aorta. Elastin is also very important in the lungs, elastic ligaments, the skin, the bladder, and elastic cartilage