The Gla26 residue of protein C is required for the binding of protein C to thrombomodulin and endothelial cell protein C receptor, but not to protein S and factor Va.
A functionally defective protein C (PC)-Mie, detected the plasma of a patient with hereditary thrombophilia, has Lys substituted for gamma-carboxyglutamic acid (Gla)26 residue. The activation rate of PC-Mie by Protac or thrombin in the absence of Ca2+ and that by thrombin with native thrombomodulin (TM), recombinant soluble truncated TM or on cultured endothelial cells in the presence of Ca2+ were all apparently lower than that of normal PC. The anticoagulant activity of Protac-activated PC (APC)-Mie on the plasma clotting time and the rate of inactivation of factor Va by APC-Mie in the presence of phospholipids were lower than those seen with normal APC. APC-Mie and normal APC bound equally to protein S and to biotinyl-factor Va. However, neither PC-Mie nor APC-Mie bound to phospholipids and to cultured human endothelial cells. It was similar to that observed with Gladomainless PC/APC, but different from that seen with normal PC/APC. These results suggest that Gla26-dependent conformation is required for the binding of PC/APC to phospholipids, TM and the surface of endothelial cell PC/APC receptor, but not to protein S and factor Va.
Nishioka
J
J
Department of Molecular Pathobiology, Mie University School of Medicine, Japan.
Ido
M
M
Hayashi
T
T
Suzuki
K
K
D015055:1-Carboxyglutamic Acid / Q000502:physiology*; D001665:Binding Sites; D001779:Blood Coagulation Factors; D001780:Blood Coagulation Tests; D004730:Endothelium, Vascular / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D015943:Factor Va / Q000378:metabolism*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D008239:Lysine; D008563:Membrane Lipids / Q000378:metabolism; D010455:Peptides / Q000494:pharmacology; D010743:Phospholipids / Q000378:metabolism; D017354:Point Mutation; D011485:Protein Binding; D011486:Protein C / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D017293:Protein S / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013329:Structure-Activity Relationship; D013917:Thrombin / Q000494:pharmacology; D013923:Thromboembolism / Q000235:genetics; D018180:Thrombomodulin / Q000378:metabolism*
D001779:Blood Coagulation Factors; D036341:Intercellular Signaling Peptides and Proteins; D008563:Membrane Lipids; D010455:Peptides; D010743:Phospholipids; D011486:Protein C; D017293:Protein S; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; D018180:Thrombomodulin; C091963:activated protein C receptor; C049647:snake venom protein C activator; D015055:1-Carboxyglutamic Acid; D015943:Factor Va; D013917:Thrombin; D008239:Lysine