This gene encodes subunit A of the coagulation factor XIII that catalyzes the final step of the blood coagulation pathway. The encoded protein associates with subunit B to form a heterotetrameric proenzyme that undergoes thrombin-mediated proteolysis to generate active factor XIIIa. The transglutaminase activity of factor XIIIa is required for the calcium-dependent crosslinking of fibrin, leading to the formation of a clot. Mice lacking the encoded protein display impaired reproduction and reduced survival due to bleeding episodes, hematothorax, hematoperitoneum and subcutaneous hemorrhage. Additionally, mice lacking the encoded protein exhibit impaired wound healing and inadequate healing of myocardial infarction. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Sep 2015]