PathwayStep722 PathwayStep723 PathwayStep720 PathwayStep721 PathwayStep726 PathwayStep727 PathwayStep724 PathwayStep725 PathwayStep729 PathwayStep728 PathwayStep730 PathwayStep715 PathwayStep716 PathwayStep718 PathwayStep717 PathwayStep719 activated thrombin (factor IIa) + thrombomodulin -> activated thrombin:thrombomodulin thrombin:cleaved antithrombin III:heparin -> thrombin:cleaved antithrombin III + heparin factor Va -> factor Vi protein C -> activated protein C + protein C heavy chain activation peptide thrombin:antithrombin III:heparin -> thrombin:cleaved antithrombin III:heparin prothrombin -> activated thrombin (factor IIa) + thrombin activation peptide (Xa catalyst) prothrombin -> activated thrombin (factor IIa) + thrombin activation peptide (prothrombinase catalyst) fibrinogen -> fibrin monomer + 2 fibrinopeptide A + 2 fibrinopeptide B factor V -> factor Va + factor V activation peptide factor Va + factor Xa -> Va:Xa complex (prothrombinase) factor XIII cleaved tetramer + 2 Ca++ -> factor XIIIa + 2 factor XIII B chain fibrin multimer -> fibrin multimer, crosslinked + NH4+ n fibrin monomers -> fibrin multimer factor XIII -> factor XIII cleaved tetramer + 2 factor XIII A activation peptides antithrombin III + heparin -> antithrombin III:heparin activated thrombin (factor IIa) + antithrombin III:heparin -> thrombin:antithrombin III:heparin Common Pathway Authored: D'Eustachio, P, 2004-08-24 14:00:00 GENE ONTOLOGYGO:0007596 Pubmed1931959 Reactome Database ID Release 43140875 Reactome, http://www.reactome.org ReactomeREACT_1439 The common pathway consists of the cascade of activation events leading from the formation of activated factor X to the formation of active thrombin, the cleavage of fibrinogen by thrombin, and the formation of cleaved fibrin into a stable multimeric, cross-linked complex. Thrombin also efficiently catalyzes the activation of several factors required earlier in the clotting cascade, thus acting in effect as a positive regulator of clotting. At the same time, thrombin activates protein C, which in turn catalyzes the inactivation of several of these upstream factors, thereby limiting the clotting process. Thrombin can also be trapped in a stable, inactive complex with antithrombin-3, a circulating blood protein. The quantitative interplay among these positive and negative modulators is critical to the normal regulation of clotting, facilitating the rapid formation of a protective clot at the site of injury, while limiting and physically confining the process.<br>These events are outlined in the drawing: black arrows connect the substrates (inputs) and products (outputs) of individual reactions, and blue lines connect output activated enzymes to the other reactions that they catalyze.