This gene encodes a vitamin K-dependent serine protease that plays a critical role in the extrinsic pathway of blood coagulation. Upon contact with tissue factor III (TF III), the encoded protein forms an activated complex termed TF-FVIIa that initiates the coagulation cascade involving other coagulation factors, ultimately resulting in a fibrin clot. Complete lack of the encoded protein in mice results in in perinatal lethality due to bleeding from normal blood vessels. [provided by RefSeq, Apr 2015]