F9 - coagulation factor IX

This gene encodes a vitamin K-dependent serine protease that plays a critical role in the intrinsic pathway of blood coagulation. The encoded protein is an inactive zymogen that is activated by coagulation factor XIa to generate factor IXa, a heterodimer containing heavy and light chains. In association with factor VIII, membrane phospholipids and calcium ions, factor IXa cleaves the inactive zymogen factor X to generate active factor Xa. Genetic deletion of this gene in mice results in a severe bleeding phenotype. Alternative splicing of this gene results in multiple transcript variants. [provided by RefSeq, Apr 2015]