Factor XIII 1330137 223564319 2008-07-04T17:16:15Z DOI bot 6652755 Citation maintenance. Formatted: author, title. You can [[WP:DOI|use this bot]] yourself! Please [[User:DOI_bot/bugs|report any bugs]]. [[Image:Factor XIII.png|right|thumb|250px|Factor XIII crosslinks fibrin]] {{protein | Name = coagulation factor XIII, A1 polypeptide | caption = | image = | width = | HGNCid = 3531 | Symbol = F13A1 | AltSymbols = F13A | EntrezGene = 2162 | OMIM = 134570 | RefSeq = NM_000129 | UniProt = P00488 | PDB = | ECnumber = | Chromosome = 6 | Arm = p | Band = 24 | LocusSupplementaryData = .2-p23 }} {{protein | Name = coagulation factor XIII, B polypeptide | caption = | image = | width = | HGNCid = 3534 | Symbol = F13B | AltSymbols = | EntrezGene = 2165 | OMIM = 134580 | RefSeq = NM_001994 | UniProt = P05160 | PDB = | ECnumber = | Chromosome = 1 | Arm = q | Band = 31 | LocusSupplementaryData = -q32.1 }} '''Factor XIII''' or '''fibrin stabilizing factor''' is an [[enzyme]] ({{EC number|2.3.2.13}}) of the [[coagulation|blood coagulation system]] that crosslinks [[fibrin]]. When [[thrombin]] has converted fibrinogen to fibrin, the latter forms a proteinaceous network in which every E-unit is crosslinked to only ''one'' D-unit. Factor XIII is activated by thrombin into factor XIIIa; its activation into Factor XIIIa requires [[calcium in biology|calcium]] as a [[Cofactor (biochemistry)|cofactor]]. FXIII is known also as Laki-Lorand factor, after the scientists who first proposed its existence in 1948.<ref name=Laki>Laki K, Lorand L. On the solubility of fibrin clots. ''Science'' 1948;108:280.</ref> A 2005 conference recommended standardization of nomenclature.<ref name=Muszbek>{{cite journal | author = Muszbek, L.| title = Factor XIII: recommended terms and abbreviations | journal = J Thromb Haemost | volume = 5| issue = | pages = 181| year = 2007| pmid = 16938124| doi = 10.1111/j.1538-7836.2006.02182.x}}</ref> ==Genetics== Zymogene factor XIII is a 320000 M<sub>r</sub> glycoprotein tetramer consisting of twice two subunits (2 A and 2 B),<ref name=Muszbek/> the [[gene]]s for which are on different [[chromosome]]s: * A subunit (6p25-p24). The [[transglutaminase]] part; this adds an alkyl group to the nitrogen on a [[glutamine]] residue, which binds in turn with a [[lysine]] on the other chain. The molecular weight of the A chain is approximately 83000. * B subunit (1q31-q32.1). This has no clear enzymatic activity, and may serve as a carrier for the A subunit. The molecular weight of the B chain is approximately 76500. ==Physiology== Typical concentrations of FXIII in plasma is 10 μg/ml (2A2B heterodimer), while the concentration of free B chain is 22 μg/ml. FXIII has a long half life, ranging from 5-9 days. It is present in plasma, [[platelet]]s, and [[monocyte]]s, as well as [[macrophage]]s and bone marrow precursors of these cell types.<ref name=Muszbek/> A clot that has not been stabilized by FXIIIa is soluble in 5 mol/L [[urea]], while a stabilized clot is resistant to this phenomenon.<ref name=Laki/> ==Diagnostic use== Factor XIII levels are not measured routinely, but may be considered in patients with an unexplained bleeding tendency. As the enzyme is quite specific for monocytes and macrophages, determination of the presence of factor XIII may be used to identify and classify malignant diseases involving these cells.<ref name=Muszbek/> ==See also== * [[Factor XIII deficiency]] * [[D-dimer]] ==References== <references/> ==External links== * [http://www.hemophilia.org/bdi/bdi_types11.htm Factor XIII deficiency at hemophilia.org] * {{eMedicine|med|3491}} {{Coagulation}} {{Acyltransferases}} [[Category:Coagulation system]] [[Category:EC 2.3.2]] [[de:Fibrinstabilisierender Faktor]] [[fr:Facteur Laki-Lorand]] [[sv:Faktor XIII]]