Novel APC-cleavage sites in FVa providing insights into mechanisms of action of APC and its cofactor protein S.

Sinh Tran, Björn Dahlbäck

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskriftPeer review

Sammanfattning

BACKGROUND: Activated protein C (APC) inhibits factor Va (FVa) by cleaving at Arg306, Arg506 and Arg679. Protein S serves as cofactor, in particular for the Arg306 site, and a protein S-mediated relocation of the active site of APC closer to the membrane has been proposed as a mechanism. Recently, it was demonstrated that FVa, which was mutated at all three APC-cleavage sites (FVa-306Q/506Q/679Q), could still be cleaved by APC. These sites were close to Arg306 and Arg506 but not further defined.

OBJECTIVE: To identify and characterize the additional APC-cleavage sites in FVa.

METHODS: The cDNA for FV-306Q/506Q/679Q was used as a template to create FV variants with one or more possible cleavage sites being mutated. The FV variants were expressed and their sensitivity for APC characterized functionally and with Western blotting.

RESULTS: The additional APC-cleavage sites were located at Lys309, Arg313, Arg316, Arg317 and Arg505. FVa-306Q/309Q/313Q/316Q/317Q/505Q/506Q/679Q (denoted 8M-FVa) was APC resistant. To investigate individual sites, they were mutated back using 8M-FV as a template. The kinetics of APC-degradation of these variants demonstrated that protein S was equally efficient in enhancing the APC effect for all the novel sites.

CONCLUSIONS: Multiple APC-cleavage sites close to Arg306 and a single site close to Arg506 were identified. Protein S was equally efficient as APC cofactor for all novel sites. The stimulation by protein S of the Arg505 cleavage argues against a specific protein S-mediated stimulation of cleavage at Arg306 due to relocation of the APC active site closer to the membrane.

Originalspråkengelska
Sidor (från-till)129-136
Antal sidor8
TidskriftJournal of Thrombosis and Haemostasis
Volym8
Nummer1
DOI
StatusPublished - 2010

Ämnesklassifikation (UKÄ)

  • Läkemedelskemi

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