Importance of protein S and phospholipid for activated protein C-mediated cleavages in factor Va.
The procoagulant function of activated factor V (FVa) is inhibited by activated protein C (APC) through proteolytic cleavages at Arg(306), Arg(506), and Arg(679). The effect of APC is potentiated by negatively charged phospholipid membranes and the APC cofactor protein S. Protein S has been reported to selectively stimulate cleavage at Arg(306), an effect hypothesized to be related to reorientatio