Effects of gamma-carboxyglutamic acid and epidermal growth factor-like modules of factor IX on factor X activation. Studies using proteolytic fragments of bovine factor IX
Factor IX is a vitamin K-dependent zymogen of a serine protease. The NH2-terminal half of the molecule consists of a Ca(2+)-binding gamma-carboxyglutamic acid (Gla)-containing module and two modules homologous to the epidermal growth factor (EGF) precursor. To elucidate the role of these non-catalytic modules of factor IXa beta in factor X activation, we have isolated and characterized fragments o