This carinactivase-like calcium-dependent prothrombin (F2) activator activates prothrombin via recognition of the calcium ion bound conformation of its gamma-carboxyglutamic acid (GLA) domain, and the subsequent conversion of prothrombin to active thrombin is catalyzed by the catalytic subunit. Binds 1 zinc ion per subunit. Heterodimer of a metalloproteinase subunit and a regulatory subunit comprising two homologous disulfide-linked lectins (AC P81798). Expressed by the venom gland. Belongs to the venom metalloproteinase (M12B) family. P-III subfamily. P-IIId sub-subfamily.