What is Collagen?
Collagen is a major structural protein found in connective tissue, skin, tendon, and bone.alpha collagen It plays a role in essential bodily functions, including tissue repair and signaling between cells.alpha collagen The body makes collagen naturally, but supplements and foods containing it can also help maintain healthy skin, hair, bones, and joints. Some studies suggest that it may also help slow the aging process, and reduce inflammation, and increase bone mineral density in people with low bone mass density.

In humans, collagen is produced in the liver, pancreas, and bone marrow.alpha collagen It is then secreted into the bloodstream, where it reaches tissues throughout the body. Once in tissues, the collagen molecules form long, thin fibers that provide support and structure. The collagen fibers are stabilized by cross-links between adjacent collagen molecules. These bonds are formed by the covalent attachment of carboxyl groups from lysine to arginine residues in the collagen chain. These chains are connected by glycosaminoglycan chains, which may be chondroitin or heparan sulfate.

The primary collagen of cartilages is a homotrimer of three identical 1 (II) chains, which are encoded by the COL2A1 gene.alpha collagen However, the collagen matrix of cartilages and other fibroblast-derived tissues is built by multiple different types of collagen proteins, which contain a variety of 1 (II) chain variants as well as a number of 2(V), 3(VII), 4(XI), 5(XIV), and 7(XVIII) chains. These different chain variants can be identical or different to form homotrimers and heterotrimers, respectively.

These diverse protein isoforms can be assembled into a broad range of fibril structures that have many biological functions.alpha collagen The 2(IV) chains of the NC1 domain form a high-density network that is resistant to cell penetration and provides mechanical stability in the dermal layer of skin. In addition, the 1(XI) chains of collagen VI are assembled into a hexameric network that binds heparan sulfate and chondroitin sulfate glycosaminoglycans to form proteoglycans, which are important constituents of the glomerular basement membrane.

Autoantibodies against specific collagens are associated with several autoimmune disorders, including epidermolysis bullosa acquisita, and the inflammatory lung disease Goodpasture syndrome (glomerulonephritis and pulmonary hemorrhage).alpha collagen The 3(IV) chains of collagen IV are also recognized by anti-glomerular basement membrane antibodies in patients with nephropathy and hepatocellular carcinoma.