Thromb Haemost 2005; 93(01): 40-47
DOI: 10.1160/TH04-07-0435
Blood Coagulation, Fibrinolysis and Cellular Haemostasis
Schattauer GmbH

Two parallel prothrombin activator systems in Australian rough-scaled snake, Tropidechis carinatus

Structural comparison of venom prothrombin activator with blood coagulation factor X
Md. Abu Reza
1   Protein Science Laboratory, Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore
,
Sanjay Swarup
1   Protein Science Laboratory, Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore
,
Manjunatha R. Kini
1   Protein Science Laboratory, Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore
2   Department of Biochemistry and Molecular Biophysics, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia USA
› Author Affiliations

Financial support: This work was supported by the Academic Research Grants from the National University of Singapore
Further Information

Publication History

Received 20 July 2004

Accepted after revision 11 November 2004

Publication Date:
14 December 2017 (online)

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Summary

It is uncommon for similar pathways/systems to be involved in highly divergent functions within single organisms. Earlier, we have shown that trocarin D, a venom prothrombin activator, from the Australian rough-scaled snake Tropidechis carinatus, is structurally and functionally similar to the blood coagulation factor Xa (FXa). The presence of a haemostatic system in these snakes implies that they have two parallel prothrombin activating systems: one in the plasma, that participates in the life saving process of blood clotting and the other in their venom, where it acts as a toxin. Here, we report the complete cDNA sequence encoding the blood coagulation factor X (FX) from the liver of T. carinatus. Deduced T. carinatus FX sequence shows ~80% identity with trocarin D but ~50% identity with the mammalian FX. Our present study confirms the presence of two separate genes – one each for FX and trocarin D, that code for similar proteins in T. carinatus snake. These two genes have different expression sites and divergent uses suggesting that snake venom prothrombin activators have probably evolved by the duplication of the liver FX gene and subsequently marked for tissue-specific expression in the venom gland.