Elastin is a polymeric protein and is the main component of the extracellular matrix of arteries.It is synthesized and secreted as a soluble, single-chain protein (tropoelastin), which undergoes a number of post-translational modifications prior to its organization into an elastic fiber in the extracellular space. Elastin performs a regulatory function during arterial development by controlling proliferation of smooth muscle and stabilizing arterial structure. It imparts elasticityto the connective tissue. During aging, the elasticity of connective tissue is reduced because of the cross-linking of collagenous fibers with elastin. The abnormal accumulation of elastic tissue in blood vessels is found in atherosclerosis and hypertension.