Identification of the Protein C/Activated Protein C Binding Sites on the Endothelial Cell Protein C Receptor IMPLICATIONS FOR A NOVEL MODE OF LIGAND RECOGNITION BY A MAJOR HISTOCOMPATIBILITY COMPLEX CLASS 1-TYPE RECEPTOR*

The endothelial cell protein C receptor (EPCR) is an endothelial cell-specific transmembrane protein that binds both protein C and activated protein C (APC). EPCR regulates the protein C anticoagulant pathway by binding protein C and augmenting protein C activation by the thrombin-thrombomodulin complex. EPCR is homologous to the MHC class 1/CD1 family, members of which contain two alpha-helices that sit upon an 8-stranded beta-sheet platform. …