Uniquely amongst vitamin K-dependent coagulation proteins, protein C interacts via its Gla domain both with a receptor, the endothelial cell protein C receptor (EPCR), and with phospholipids. We have studied naturally occurring and recombinant protein C Gla domain variants for soluble (s)EPCR binding, cell surface activation to activated protein C (APC) by the thrombin–thrombomodulin complex, and phospholipid dependent factor Va (FVa) inactivation by APC, to establish if these functions are concordant. .
