Editing Collagen (section)

==Types==
As of 2011, 28 types of human collagen have been identified, described, and classified according to their structure.<ref name="Ricard-Blum">{{cite journal | vauthors = Ricard-Blum S | title = The collagen family | journal = Cold Spring Harbor Perspectives in Biology | volume = 3 | issue = 1 | pages = a004978 | date = January 2011 | pmid = 21421911 | pmc = 3003457 | doi = 10.1101/cshperspect.a004978 }}</ref> This diversity shows collagen's diverse functionality.<ref name="Franzke">{{cite journal | vauthors = Franzke CW, Bruckner P, Bruckner-Tuderman L | title = Collagenous transmembrane proteins: recent insights into biology and pathology | journal = Journal of Biological Chemistry | volume = 280 | issue = 6 | pages = 4005–4008 | date = February 2005 | pmid = 15561712 | doi = 10.1074/jbc.R400034200 | doi-access = free }}</ref> All of the types contain at least one [[triple helix]].<ref name="Ricard-Blum" /> Over 90% of the collagen in [[human body|humans]] is [[type I & III collagen]].<ref>Sabiston textbook of surgery board review, 7th edition. Chapter 5 wound healing, question 14</ref>
* Fibrillar (type I, II, III, V, XI)
* Non-fibrillar
** [[FACIT collagen|FACIT]] (fibril-associated collagens with interrupted triple helices) (types IX, XII, XIV, XIX, XXI)
** Short-chain (types VIII, X)
** [[Basement membrane]] (type IV)
** [[Multiplexin]] (multiple triple helix domains with interruptions) (types XV, XVIII)
** MACIT (membrane-associated collagens with interrupted triple helices) (types XIII, XVII)
** Microfibril-forming (type VI)
** [[Anchoring fibrils]] (type VII)

The five most common types are:<ref>{{cite journal | vauthors = Ashokkumar M, Ajayan PM |title=Materials science perspective of multifunctional materials derived from collagen |journal=International Materials Reviews |date=3 April 2021 |volume=66 |issue=3|pages=160–87 |doi=10.1080/09506608.2020.1750807 |bibcode=2021IMRv...66..160A |s2cid=216270520 |url=https://www.tandfonline.com/doi/full/10.1080/09506608.2020.1750807 |issn=0950-6608}}</ref>
* [[Type I collagen|Type I]]: skin, [[tendon]], vasculature, organs, [[bone]] (main component of the organic part of bone)
* [[Type II collagen|Type II]]: [[cartilage]] (main collagenous component of cartilage)
* [[Collagen, type III, alpha 1|Type III]]: reticulate (main component of [[reticular fiber]]s), commonly found alongside type I
* [[Type IV collagen|Type IV]]: forms basal lamina, the epithelium-secreted layer of the [[basement membrane]]
* [[Type-V collagen|Type V]]: cell surfaces, hair, and [[placenta]]