factor Xa factor X activation of factor X by VIIIa:IXa Authored: D'Eustachio, P, 2005-01-20 14:44:36 EC Number: 3.4.21 Edited: D'Eustachio, P, 0000-00-00 00:00:00 Factor IXa, in a complex with factor VIIIa on the surfaces of activated platelets (the "intrinsic tenase complex"), catalyzes the formation of activated factor X with high efficiency. The amino terminal part of the heavy chain of factor X, the factor X activation peptide, is released. (This peptide has no known function.) Pubmed2110473 Reactome Database ID Release 43158164 Reactome, http://www.reactome.org ReactomeREACT_1668 factor X -> factor Xa + factor X activation peptide (VIIIa:IXa catalyst) has a Stoichiometric coefficient of 20