Factor XIII

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coagulation factor XIII, A1 polypeptide
Identifiers
Symbol(s)	F13A1 F13A
Entrez	2162
OMIM	134570
RefSeq	NM_000129
UniProt	P00488
Other data
Locus	Chr. 6 p24.2-p23

coagulation factor XIII, B polypeptide
Identifiers
Symbol(s)	F13B
Entrez	2165
OMIM	134580
RefSeq	NM_001994
UniProt	P05160
Other data
Locus	Chr. 1 q31-q32.1

Factor XIII or fibrin stabilizing factor is an enzyme (EC 2.3.2.13) of the 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 as a cofactor.

FXIII is known also as Laki-Lorand factor, after the scientists who first proposed its existence in 1948.^[1]

1 Genetics
2 Physiology
3 Role in disease
4 See also
5 Reference
6 External links

[edit] Genetics

Factor XIII crosslinks fibrin

Zymogene factor XIII is a 320000 M_r glycoprotein consisting of twice two subunits (2 A and 2 B), the genes for which are on different chromosomes:

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.

[edit] 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.

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.^[1]

[edit] Role in disease

Factor XIII deficiency may occur very rarely, and can cause a severe bleeding tendency. Incidence is 1 in a million to 1 in 5 million people. Most are due to mutations in the A subunit. Administration of recombinant A subunit improves clot stability and may become a therapeutic option for patients with this condition^[2].

[edit] See also

D-dimer

[edit] Reference

^ ^a ^b Laki K, Lorand L. On the solubility of fibrin clots. Science 1948;108:280.
^ Lovejoy A, Reynolds T, Visich J, Butine M, Young G, Belvedere M, Blain R, Pederson S, Ishak L, Nugent D (2006). "Safety and pharmacokinetics of recombinant factor XIII-A2 administration in patients with congenital factor XIII deficiency.". Blood 108 (1): 57-62. PMID 16556896.