{"symbol":"F13A1","synonyms":["F13A"],"name":"coagulation factor XIII, A1 polypeptide","description":"This gene encodes the coagulation factor XIII A subunit. Coagulation factor XIII is the last zymogen to become activated in the blood coagulation cascade. Plasma factor XIII is a heterotetramer composed of 2 A subunits and 2 B subunits. The A subunits have catalytic function, and the B subunits do not have enzymatic activity and may serve as plasma carrier molecules. Platelet factor XIII is comprised only of 2 A subunits, which are identical to those of plasma origin. Upon cleavage of the activation peptide by thrombin and in the presence of calcium ion, the plasma factor XIII dissociates its B subunits and yields the same active enzyme, factor XIIIa, as platelet factor XIII. This enzyme acts as a transglutaminase to catalyze the formation of gamma-glutamyl-epsilon-lysine crosslinking between fibrin molecules, thus stabilizing the fibrin clot. It also crosslinks alpha-2-plasmin inhibitor, or fibronectin, to the alpha chains of fibrin. Factor XIII deficiency is classified into two categories: type I deficiency, characterized by the lack of both the A and B subunits; and type II deficiency, characterized by the lack of the A subunit alone. These defects can result in a lifelong bleeding tendency, defective wound healing, and habitual abortion. [provided by RefSeq, Jul 2008]","ncbiEntrezGeneId":2162,"ncbiEntrezGeneUrl":"http://www.ncbi.nlm.nih.gov/gene/2162","proteins":[{"symbol":"F13A_HUMAN","href":"/api/1.0/protein/F13A_HUMAN"}],"hgncRootFamilies":[{"name":"Transglutaminases (TGM)","href":"/api/1.0/gene_family/Transglutaminases+%28TGM%29"}]}