<P> Collagen fibrils / aggregates are arranged in different combinations and concentrations in various tissues to provide varying tissue properties . In bone, entire collagen triple helices lie in a parallel, staggered array . 40 nm gaps between the ends of the tropocollagen subunits (approximately equal to the gap region) probably serve as nucleation sites for the deposition of long, hard, fine crystals of the mineral component, which is hydroxylapatite (approximately) Ca (OH) (PO). Type I collagen gives bone its tensile strength . </P> <P> Collagen - related diseases most commonly arise from genetic defects or nutritional deficiencies that affect the biosynthesis, assembly, postranslational modification, secretion, or other processes involved in normal collagen production . </P> <Table> Genetic Defects of Collagen Genes <Tr> <Td> Type </Td> <Td> Notes </Td> <Td> Gene (s) </Td> <Td> Disorders </Td> </Tr> <Tr> <Td> </Td> <Td> This is the most abundant collagen of the human body . It is present in scar tissue, the end product when tissue heals by repair . It is found in tendons, skin, artery walls, cornea, the endomysium surrounding muscle fibers, fibrocartilage, and the organic part of bones and teeth . </Td> <Td> COL1A1, COL1A2 </Td> <Td> Osteogenesis imperfecta, Ehlers--Danlos syndrome, Infantile cortical hyperostosis a.k.a. Caffey's disease </Td> </Tr> <Tr> <Td> II </Td> <Td> Hyaline cartilage, makes up 50% of all cartilage protein . Vitreous humour of the eye . </Td> <Td> COL2A1 </Td> <Td> Collagenopathy, types II and XI </Td> </Tr> <Tr> <Td> III </Td> <Td> This is the collagen of granulation tissue and is produced quickly by young fibroblasts before the tougher type I collagen is synthesized . Reticular fiber . Also found in artery walls, skin, intestines and the uterus </Td> <Td> COL3A1 </Td> <Td> Ehlers--Danlos syndrome, Dupuytren's contracture </Td> </Tr> <Tr> <Td> IV </Td> <Td> Basal lamina; eye lens . Also serves as part of the filtration system in capillaries and the glomeruli of nephron in the kidney . </Td> <Td> COL4A1, COL4A2, COL4A3, COL4A4, COL4A5, COL4A6 </Td> <Td> Alport syndrome, Goodpasture's syndrome </Td> </Tr> <Tr> <Td> V </Td> <Td> Most interstitial tissue, assoc . with type I, associated with placenta </Td> <Td> COL5A1, COL5A2, COL5A3 </Td> <Td> Ehlers--Danlos syndrome (Classical) </Td> </Tr> <Tr> <Td> VI </Td> <Td> Most interstitial tissue, assoc . with type I </Td> <Td> COL6A1, COL6A2, COL6A3, COL6A5 </Td> <Td> Ulrich myopathy, Bethlem myopathy, Atopic dermatitis </Td> </Tr> <Tr> <Td> VII </Td> <Td> Forms anchoring fibrils in dermoepidermal junctions </Td> <Td> COL7A1 </Td> <Td> Epidermolysis bullosa dystrophica </Td> </Tr> <Tr> <Td> VIII </Td> <Td> Some endothelial cells </Td> <Td> COL8A1, COL8A2 </Td> <Td> Posterior polymorphous corneal dystrophy 2 </Td> </Tr> <Tr> <Td> IX </Td> <Td> FACIT collagen, cartilage, assoc . with type II and XI fibrils </Td> <Td> COL9A1, COL9A2, COL9A3 </Td> <Td> EDM2 and EDM3 </Td> </Tr> <Tr> <Td> X </Td> <Td> Hypertrophic and mineralizing cartilage </Td> <Td> COL10A1 </Td> <Td> Schmid metaphyseal dysplasia </Td> </Tr> <Tr> <Td> XI </Td> <Td> Cartilage </Td> <Td> COL11A1, COL11A2 </Td> <Td> Collagenopathy, types II and XI </Td> </Tr> <Tr> <Td> XII </Td> <Td> FACIT collagen, interacts with type I containing fibrils, decorin and glycosaminoglycans </Td> <Td> COL12A1 </Td> <Td>--</Td> </Tr> <Tr> <Td> XIII </Td> <Td> Transmembrane collagen, interacts with integrin a1b1, fibronectin and components of basement membranes like nidogen and perlecan . </Td> <Td> COL13A1 </Td> <Td>--</Td> </Tr> <Tr> <Td> XIV </Td> <Td> FACIT collagen, also known as undulin </Td> <Td> COL14A1 </Td> <Td>--</Td> </Tr> <Tr> <Td> XV </Td> <Td>--</Td> <Td> COL15A1 </Td> <Td>--</Td> </Tr> <Tr> <Td> XVI </Td> <Td>--</Td> <Td> COL16A1 </Td> <Td>--</Td> </Tr> <Tr> <Td> XVII </Td> <Td> Transmembrane collagen, also known as BP180, a 180 kDa protein </Td> <Td> COL17A1 </Td> <Td> Bullous pemphigoid and certain forms of junctional epidermolysis bullosa </Td> </Tr> <Tr> <Td> XVIII </Td> <Td> Source of endostatin </Td> <Td> COL18A1 </Td> <Td>--</Td> </Tr> <Tr> <Td> XIX </Td> <Td> FACIT collagen </Td> <Td> COL19A1 </Td> <Td>--</Td> </Tr> <Tr> <Td> XX </Td> <Td>--</Td> <Td> COL20A1 </Td> <Td>--</Td> </Tr> <Tr> <Td> XXI </Td> <Td> FACIT collagen </Td> <Td> COL21A1 </Td> <Td>--</Td> </Tr> <Tr> <Td> XXII </Td> <Td>--</Td> <Td> COL22A1 </Td> <Td>--</Td> </Tr> <Tr> <Td> XXIII </Td> <Td> MACIT collagen </Td> <Td> COL23A1 </Td> <Td>--</Td> </Tr> <Tr> <Td> XXIV </Td> <Td>--</Td> <Td> COL24A1 </Td> <Td>--</Td> </Tr> <Tr> <Td> XXV </Td> <Td>--</Td> <Td> COL25A1 </Td> <Td>--</Td> </Tr> <Tr> <Td> XXVI </Td> <Td>--</Td> <Td> EMID2 </Td> <Td>--</Td> </Tr> <Tr> <Td> XXVII </Td> <Td>--</Td> <Td> COL27A1 </Td> <Td>--</Td> </Tr> <Tr> <Td> XXVIII </Td> <Td>--</Td> <Td> COL28A1 </Td> <Td>--</Td> </Tr> <Tr> <Td> XXIX </Td> <Td> Epidermal collagen </Td> <Td> COL29A1 </Td> <Td> Atopic Dermatitis </Td> </Tr> </Table> <Tr> <Td> Type </Td> <Td> Notes </Td> <Td> Gene (s) </Td> <Td> Disorders </Td> </Tr>

Where is collagen found in the human body