Factor IXa

The crystal structure of Factor IXa complexed with p-amino-benzamidine.^[1]

Function

The Factor IX protein is a serine protease that is part of the blood coagulation cascade.

Disease

Defects in the F9 gene, coding for Factor IX, result in the disease Hemophilia B. The F9 gene is located on the X chromosome. Hemophilia B is distinct from Hemophilia A, which results from defects in the F8 gene coding for Factor VIII, also located on the X chromosome. Factor IXa (the activated, clipped form of Factor IX) interacts with Factor VIIIa to form an active protease, which intern clips Factor X to its active form, Factor Xa.

Relevance

Structural highlights

This is a sample scene created with SAT to by Group, and another to make of the protein. You can make your own scenes on SAT starting from scratch or loading and editing one of these sample scenes. Here is an The catalytic triad at the active site is comprised of His57, Asp102 and Ser1985 is highlighted. Now . The His borrows an H from Her, which now attacks at the substrate. In this case the active site is blocked by the inhibitor, p-amino-benzamidine. Mutation of C252S results in Hemophilia B, probably due to destabilization of the loop including the His of the catalytic triad. A mutation of T194A exhibits increased activity and stability and appears to enhance the risk for Deep Vein Thrombosis and stroke.