William H. Kane
Defects in coagulation factor V that result in resistance to activatd protein C (APC) are the most common know genetic risk factor for thrombois. In order to understand the mechanisms regulating the prothrombinase complex we have cloned and expressed the gene for human factor V. Our research is foucused in two main areas. First, we are investigating mechanisms that lead to activation of factor V as well as characerizing the binding sites for prothrombin, factor Xa, phosphatidyl serine and platelets. We are also investigating the role of metal ions (calcium and copper and post translation modifications (tyrosine sulfation and carbohydrate ) in regulating procoagulant activity. We are expressing individual domains of factor V using insect cells in order to obtain protein preparations that will be suitable for crystallization and x-ray diffraction analysis. Second, we are investigating the inactivation of the prothrombinase complex by the protein C pathway. We are using the factor V expression systems established in our laboratory to characterize the functional consequences of factor V mutations associated with thrombophilia and protein C resistance. These expression systems are also being used to define the regions of factor V that are important in the expression of Protein C cofactor-2 activity and the interaction of factor Va with activated protein C and protein S. We will also create trnsgenic murine models for protein C resistance. The phyiological consequences of these factor v mutations will be investigated in murine thrombosis models. the results of these studies will also provide new insights into the molecular mechanisms that regulate the prothrombinase complex.