The extracellular matrix (ECM) is the external framework found between individual cells that comprise higher order structures like tissues and organs. The ECM composition of vertebrates is dominated by a class of molecules known as collagens - each with unique features suited for a particular function and location. Collagen proteins are made up of three subunit polypeptides that vary in length. Through a unique repeated (Gly-X-Y) sequence, these components associate to form a structurally regular triple helix.
