Factor 3 and 7GARY OH

Clotting Cascade

Finalizes in fibrin clot formation 2 pathways:

1)Intrinsic 2)Extrinsic pathway

Both pathways finalize in Factor 10a formation Both pathways involve a common pathway of prothrombin to thrombin formation.

Factor 3 and 7 deals specifically with Extrinsic pathway activation of Factor 10 to 10a and prothrombin to thrombin.

This leads to fibrin clot formation.

Factor 3: Tissue Factor (CD1420 cluster of differentiation)

Cell surface glycoprotein Subendothelial tissue protein and on leukocytes Tissue factor is found on the outside of blood vessels - normally not exposed to

the bloodstream. Upon vessel injury, tissue factor is exposed to the blood and circulating factor

VII. Necessary for initiation of thrombin formation from zymogen prothrombin Unique from other 13 factors in blood, factor 3 is a potent initiator that is fully

functional when expressed on cell surfaces High-affinity receptor for the coagulation factor VIIa 3 distinct domains of this factor: extracellular, transmembrane, and cytoplasmic This protein is the only one in the coagulation pathway for which a congenital

deficiency has not been described (deadly)

Factor 7

Serine protease enzyme. Initiates coagulation process with Factor 3 (Tissue

Factor). Upon vessel injury, tissue factor is exposed to the

blood and circulating Factor 7. Once bound to Factor 3, Factor 7 is activated to

Factor 7a Factor 7 is vitamin K dependent and produced in

the liver. Use of warfarin or similar anticoagulants decreases hepatic synthesis of FVII.

Pathology: Factor 7 deficiency presents as a hemophilia-like bleeding disorder.

Treatments: recombinant Factor 7a for uncontrolled bleeding in hemophelia.

Factor 3 and 7 together deal specifically with Extrinsic pathway activation of Factor 10 to 10a and prothrombin to thrombin resulting finally in fibrin clot formation.

REFERENCES

Bajzar L, Morser J, Nesheim M (July 1996). TAFI, or plasma procarboxypeptidase B, couples the coagulation and fibrinolytic cascades through the thrombin-thrombomodulin complex. J. Biol. Chem. 271 (28): 16603–8.

Jakubowski HV, Owen WG (July 1989). Macromolecular specificity determinants on thrombin for fibrinogen and thrombomodulin. J. Biol. Chem. 264 (19): 11117–21.

Van den Besselaar AM, Chantarangkul V, Tripodi A (July 2010). "Thromboplastin standards". Biologicals 38 (4): 430–6.