4bxs

Structural highlights

Function

FAXC_PSETE 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).^{[1] [2]}

References

1. ↑ Rao VS, Kini RM. Pseutarin C, a prothrombin activator from Pseudonaja textilis venom: its structural and functional similarity to mammalian coagulation factor Xa-Va complex. Thromb Haemost. 2002 Oct;88(4):611-9. PMID:12362232 doi:10.1267/th02100611
2. ↑ Lechtenberg BC, Murray-Rust TA, Johnson DJ, Adams TE, Krishnaswamy S, Camire RM, Huntington JA. Crystal structure of the prothrombinase complex from the venom of Pseudonaja textilis. Blood. 2013 Jul 18. PMID:23869089 doi:10.1182/blood-2013-06-511733
3. ↑ Lechtenberg BC, Murray-Rust TA, Johnson DJ, Adams TE, Krishnaswamy S, Camire RM, Huntington JA. Crystal structure of the prothrombinase complex from the venom of Pseudonaja textilis. Blood. 2013 Jul 18. PMID:23869089 doi:10.1182/blood-2013-06-511733