Fibrin stabilizing factor

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Fibrin stabilizing factor
Fibrin stabilizing factor
Ribbon model of the A chain dimer of factor XIII, according to PDB  1EVU
Properties of human protein
Mass / length primary structure 2670 = 2 * 694 + 2 * 641 amino acids
Secondary to quaternary structure 2A + 2B
Cofactor Calcium (A)
Precursor A: (731 amino acids)
Identifier
Gene names F13A1  ; F13B
External IDs
Drug information
ATC code B02 BD07
Enzyme classification
EC, category 2.3.2.13 transferase
Response type Transfer of alkyl residues within or between proteins
Substrate Xaa-Gln-Xaa + Yaa-Lys-Yaa
Products Xaa-Glu (Xaa) -Lys (Yaa) -Yaa + NH 3
Occurrence
Homology family Transglutaminase
Parent taxon Chordates

The fibrin-stabilizing factor ( factor XIII or Laki-Lorand factor) is an enzyme and, as a coagulation factor, part of blood coagulation . It consists of two subunits, two A and two B. Its normal concentration in the blood plasma is 10 μg / ml, its half-life 5-9 days.

genetics

Scheme of the cross-linking by factor XIII

The two subunits of factor XIII are encoded by two different genes :

physiology

Thrombin converts fibrinogen to fibrin . This consists of a D-unit and two E-units bound to it on both sides. Fibrin forms a network in which each of its E units has connections to only one D unit of another fibrin molecule. Factor XIII is also activated by thrombin, together with calcium , and links the D unit of fibrin with the E units of other fibrin molecules. This is known as the retraction phase of blood clotting. Another important function of factor XIIIa is the fixation of the fibrinolysis inhibitors TAFI (Thrombin Activated Fibrinolysis Inhibitor) and alpha-2 antiplasmin in the fibrin clot. This protects the clot from premature fibrinolysis and thus also prevents bleeding. Furthermore, factor XIIIa binds various other substrates to cell surfaces, including thrombospondin, fibronectin and other proteins.

Diseases

Hereditary factor XIII deficiency is extremely rare and causes a high tendency to bleed. Acquired deficiencies, on the other hand, are not uncommon.

literature

Web links