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KMID : 0950020040300010001
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Journal of Health Science & Medical Technology
2004 Volume.30 No. 1 p.1 ~ p.9
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Mutation of individual protein C cleavage sites in Human coagulation factor Va
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Kim Sung-Wook
Lee Seung-Gwan
Lee Chang-Kyu
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Abstract
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Resistance to activated protein C (APC) is the most common inherited risk factor for venous thrombosis. In the present study we have investigated the effect of mutations of the APC cleavage sites at Arg306, Arg506 and Arg679 in the factor V heavy chain on the inactivation of factor Va by APC. Mutants R306A, R506Q and R679A were expressed using B-domain deleted factor V constructs in COS-7 cells. The specific activity of the purified mutant proteins was identical to the wild-type protein (rHFVa) and APC cleavage at the mutated sites was blocked. Characterization of these mutants using a clinical assay for APC resistance demonstrated that R506Q was resistant to APC, but that R306A and R679A were sensitive. In clotting assays, R506Q showed delayed inactivation by APC, whereas R306A showed a rapid but incomplete loss of activity. APC inactivation of R679A was rapid and indistinguishable from rHFVa. These results indicate that mutation of individual APC cleavage sites in factor Va leads to variable degrees of APC. These findings have significant implications for the identification of patients with APC resistance and the understanding of the importance of individual APC cleavage sites in regulating the activity of the prothrombinase complex.
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KEYWORD
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coagulation factor V, activated protein C, prothrombinase complex
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