Multactivase, a carinactivase-like calcium-dependent prothrombin 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. Heterodimer of a metalloproteinase subunit and a regulatory subunit comprising two homologous polypeptides disulfide-linked. Expressed by the venom gland. Belongs to the snaclec family.