Factor XIII, also known as fibrin stabilizing factor or F13, is an essential blood plasma protein involved in the process of blood clot formation and stabilization. It plays a critical role in converting soluble fibrinogen into a stable fibrin clot to prevent excessive bleeding and promote wound healing.
Factor XIII is a tetrameric enzyme complex consisting of two A subunits (FXIII-A) and two B subunits (FXIII-B). It is primarily produced by megakaryocytes and hepatocytes and circulates in the blood in an inactive proenzyme form called FXIII-A2B2. Upon activation by the thrombin-thrombomodulin complex, factor XIII is simultaneously cleaved and activated, leading to the formation of FXIIIa, the activated form of the factor.
The activated factor XIIIa acts by cross-linking fibrin monomers, which strengthens and stabilizes the fibrin clot. This cross-linking process creates stable covalent bonds between the fibrin strands, increasing the mechanical strength and integrity of the clot structure. Factor XIIIa also interacts with other blood components, such as fibronectin, to enhance clot adhesion and tissue repair.
Mutations or deficiencies in factor XIII can result in a rare inherited bleeding disorder known as congenital factor XIII deficiency. Individuals with this condition are more susceptible to prolonged bleeding, recurrent miscarriages, and poor wound healing.
In summary, factor XIII is a crucial component of the blood clotting cascade, responsible for stabilizing fibrin clots and promoting wound healing. It acts by cross-linking fibrin strands and enhancing clot adhesion, thereby playing a critical role in maintaining proper hemostasis.
