Ferritin
470107
222834124
2008-07-01T10:05:09Z
DOI bot
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{{protein
| Name = [[Ferritin light chain|ferritin, light polypeptide]]
| caption = Structure of the ferritin complex
| image = Ferritin.png
| width = 200
| HGNCid = 3999
| Symbol = [[Ferritin light chain|FTL]]
| AltSymbols =
| EntrezGene = 2512
| OMIM = 134790
| RefSeq = NM_000146
| UniProt = P02792
| PDB =
| ECnumber =
| Chromosome = 19
| Arm = q
| Band = 13.3-13.4
| LocusSupplementaryData =
}}
{{protein
| Name = [[FTH1|ferritin, heavy polypeptide 1]]
| caption =
| image =
| width =
| HGNCid = 3976
| Symbol = [[FTH1]]
| AltSymbols = FTHL6
| EntrezGene = 2495
| OMIM = 134770
| RefSeq = NM_002032
| UniProt = P02794
| PDB =
| ECnumber =
| Chromosome = 11
| Arm = q
| Band = 13
| LocusSupplementaryData =
}}
{{protein
| Name = ferritin mitochondrial
| caption =
| image =
| width =
| HGNCid = 17345
| Symbol = FTMT
| AltSymbols =
| EntrezGene = 94033
| OMIM = 608847
| RefSeq = NM_177478
| UniProt = Q8N4E7
| PDB =
| ECnumber =
| Chromosome = 5
| Arm = q
| Band = 23.1
| LocusSupplementaryData =
}}
{{Expert-verify|date=May 2008}}
'''Ferritin''' is a [[globular protein]] complex consisting of 24 protein subunits and is the main intracellular iron storage protein in both [[prokaryote]]s and [[eukaryote]]s, keeping it in a soluble and non-toxic form. Ferritin which is not combined with iron is called '''apoferritin'''.
== Description ==
Ferritin, a 450 k.Da. protein consisting of 24 subunits is present in every cell type. In vertebrates, these subunits are both the light (L) and the heavy (H) type with a apperent molecular weight of 19 kDA or 21 kDA respectively. In plants and bacteria the complex only consists of the H-chain type. Inside the ferritin shell, iron ions form [[crystallite]]s together with [[phosphate]] and [[hydroxide]] ions. The resulting particle is similar to the mineral [[ferrihydrite]]. Each ferritin complex can store about 4500 [[iron]] (Fe<sup>3+</sup>) ions.
Some ferritin complexes in [[vertebrate]]s are hetero-oligomers of two highly-related [[gene]] products with slightly different [[physiological]] properties. The ratio of the two [[homologous]] [[protein]]s in the complex depends on the relative expression levels of the two genes.
== Function==
Free iron is [[toxic]] to [[Cell (biology)|cells]] as it acts as a catalyst in the formation of free radicals from [[reactive oxygen species]] via the [[Fenton Reaction]].<ref>{{cite journal | author = Orino K, Lehman L, Tsuji Y, Ayaki H, Torti SV, Torti FM | title = Ferritin and the response to oxidative stress | journal = Biochem J | volume = 357 | issue = 1 | pages = 241–7 | year = 2001 | pmid = 11415455 | doi = 10.1042/0264-6021:3570241}}</ref> Hence organisms have evolved an elaborate set of protective mechanisms to bind iron in various [[Biological tissue|tissue]] compartments. Within cells, iron is stored complexed to protein as ferritin or [[hemosiderin]]. [[Apoferritin]] binds to free ferrous iron and stores it in the ferric state. As ferritin accumulates within cells of the [[reticuloendothelial system]], protein aggregates are formed as [[hemosiderin]]. Iron in ferritin or hemosiderin can be extracted for release by the RE cells although hemosiderin is less readily available. Under [[steady state]] conditions, the [[serum]] ferritin level correlates with total body iron stores; thus, the serum ferritin level is the most convenient laboratory test to estimate iron stores.
Ferritin is also used in materials science as a precursor in making iron [[nanoparticle]]s for [[carbon nanotube]] growth by [[chemical vapor deposition]].
== Diagnostic uses ==
[[blood plasma|Serum]] ferritin levels are measured in [[patient]]s as part of the '''iron studies''' workup for [[anemia]] and for [[restless leg syndrome]]. The ferritin levels measured have a direct correlation with the total amount of iron stored in the body (except in certain circumstances, such as [[anemia of chronic disease]]). If ferritin is high there is iron in excess, which would be [[excrete]]d in the [[stool]]. If ferritin is low there is a risk for lack in iron which sooner or later could lead to [[anemia]]. Low ferritin levels have been associated with symptoms of [[restless leg syndrome]] even in the absence of anemia.
Normal [[blood levels]] are 30-300 ng/mL for males and 15-200 ng/mL for females. ((according to clinical medicine by : Kumar & clark page 428 )) <ref>Beyond Cholesterol, Julius Torelli MD, 2005 ISBN 0-312-34863-0 p.84</ref><ref>[http://www.nlm.nih.gov/medlineplus/ency/article/003490.htm MedlinePlus Medical Encyclopedia: Ferritin<!-- Bot generated title -->]</ref>
In the setting of [[anemia]], [[serum]] ferritin is the most [[sensitivity (tests)|sensitive]] lab test for [[iron deficiency anemia]].<ref>{{cite journal | author = Guyatt G, Patterson C, Ali M, Singer J, Levine M, Turpie I, Meyer R | title = Diagnosis of iron-deficiency anemia in the elderly | journal = Am J Med | volume = 88 | issue = 3 | pages = 205–9 | year = 1990 | pmid = 2178409 | doi = 10.1016/0002-9343(90)90143-2}}</ref>
Ferritin is also used as a [[marker]] for [[iron overload disorder]]s, such as [[hemochromatosis]] and [[porphyria]] in which the ferritin level may be abnormally raised.
As ferritin is also an [[acute phase proteins|acute-phase reactant]], it is often elevated in the course of [[disease]]. A normal [[C-reactive protein]] can be used to exclude elevated ferritin caused by acute phase reactions.
Ferritin can be elevated during periods of acute [[Malnutrition|malnourishment]].<ref>{{cite journal | author = Kennedy A, Kohn M, Lammi A, Clarke S | title = Iron status and haematological changes in adolescent female inpatients with anorexia nervosa | journal = J Paediatr Child Health | volume = 40 | issue = 8 | pages = 430–2 | year = 2004 | pmid = 15265182 | doi = 10.1111/j.1440-1754.2004.00432.x}}</ref>
== See also ==
*[[Bacterioferritin]]
*[[Transferrin]]
*[[Ferritin light chain]]
==References==
<references/>
==External links==
* http://sickle.bwh.harvard.edu/iron_transport.html
{{Iron-binding proteins}}
[[Category:Blood tests]]
[[Category:Chemical pathology]]
[[Category:acute phase proteins]]
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