FEATURES

FAMILY

DESCRIPTION

Also known as FA5V_PSETE, FA5V. Snake prothrombin activator that attacks the hemostatic system of prey. This non-catalytic subunit is functionally similar to blood coagulation factor V (PubMed:12362232, PubMed:23869089). It serves as a critical cofactor for the prothrombinase activity of the catalytic subunit, which is similar to the blood coagulation factor X (PubMed:12362232, PubMed:23869089). The complex converts prothrombin to thrombin by sequential cleavage at two positions, Arg-320 followed by Arg-271 (PubMed:23869089). Cleavage at Arg-320 produces an active intermediate known as meizothrombin (PubMed:23869089). Meizothrombin is the 'second' substrate for prothrombinase, and it docks in an altered manner to present the second cleavage site (271) (PubMed:23869089). Cleavage at Arg-271 releases active thrombin from its pro-fragment (PubMed:23869089). This order of events is reversed if the protease component of prothrombinase is used on its own, suggesting that the 271 site is inherently more accessible to proteolysis (PubMed:23869089). The complex converts prothrombin to thrombin in presence but also in the absence of membrane (PubMed:23869089). Heterodimer of a light and a heavy chains; non-disulfide-linked. The interaction between the two chains is calcium-dependent (By similarity). Found in its active form associated with pseutarin-C catalytic subunit (AC Q56VR3).

EXTERNAL LINKS

FA5V

Venom prothrombin activator pseutarin-C non-catalytic subunit

FA5V

Molecular Synopsis