Factor IXa (Last Updated - 2/28/2005)

-makes up a step of the intrinsic pathway
-formed via activation of Factor IX --> this reaction is catalyzed by:
     1) Factor XIa
     2) Tissue factor (TF or Factor III) & Factor VIIa via crossover from the extrinsic pathway
-Factor IXa (along with calcium (Factor IV), phospholipids, Factors VIIIa & VIIa) in turn catalyzes the activation of Factor X to Xa

-click here to view an image of the clotting cascade

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References:

Goodman & Gilman's: The Pharmacologic Basis Of Therapeutics - 10th Edition - 2001. Chapter 55.