Collagen is a group of proteins found in animals. It is the main component of connective tissue, and is the protein that occurs the most in Mammals (around up about 30% of the whole-body protein content). Collagen is mostly found in fibrous tissues such as tendons, ligaments and skin, but is also found in the cornea, cartilage, bone and blood vessels. Collagen is commonly made in the fibroblast but can be made in other places.
Collagen is the most diverse of the four fibre protein types (collagen, elastin, fibrillin, fibronectin), with at least 12 variations. Individual collagen molecules can pack together to form collagen fibres, which is a flexible but inelastic fibres with outstanding strength.
The structure of a collagen molecule is made up of a three collagen polypeptides wounded together to form a triple-helical structure. In some cases, according to its type, these molecules can form fibrils, which have diameters of 10-300 nm. This goes further, as collagen fibrils can band up together and form collagen fibres, usually 0.5-3 µm in diameter.
- ↑ Müller, Werner E. G. (2003). "The Origin of Metazoan Complexity: Porifera as Integrated Animals"
- ↑ http://www.wisegeek.com/what-is-collagen.htm
- ↑ http://www.livestrong.com/article/75022-collagen-produced/
- ↑ Silverthorn et al.,(2014) Human Physiology An Integrated Approach, Sixth Edition, Pearson Education, 91
- ↑ Alberts B, et al. (2014) Essential Cell Biology. 4th Edition. Garland Science.