Catalytic subunit of coagulation factor X-activating enzyme, a zinc-protease enzyme that acts in hemostasis. Activates coagulation factor X (F10) by cleaving the Arg-Ile bond at position 234 and is also able to activate coagulation factor IX (F9) and protein C (PROC) by specific cleavage of Arg-Ile and Arg-Val bonds (By similarity). Specifically activates several components of the blood clotting system, including coagulation factor X, coagulation factor IX and protein C by cleavage of Arg-|-Xaa bonds. Has no action on insulin B chain. Binds 1 zinc ion per subunit. Heterotrimer; disulfide-linked. The heterotrimer consists of 1 heavy chain and 2 light chains (lectins): LC1 and LC2 (By similarity). Expressed by the venom gland. N-glycosylated. Belongs to the venom metalloproteinase (M12B) family. P-III subfamily. P-IIId sub-subfamily.