tailieunhanh - Báo cáo khoa học: Probing the interface between factor Xa and tissue factor in the quaternary complex tissue factor–factor VIIa–factor Xa–tissue factor pathway inhibitor

Bloodcoagulation is triggeredby the formationof acomplex between factor VIIa (FVIIa) and its cofactor, tissue factor (TF). TF–FVIIa is inhibited by tissue factor pathway inhibitor (TFPI) in two steps: first TFPI is bound to the active site of factor Xa (FXa), and subsequently FXa–TFPI exerts feedback inhibition of TF–FVIIa. The FXa-depend-ent inhibition of TF–FVIIa activity by TFPI leads to for-mation of the quaternary complex TF–FVIIa–FXa–TFPI. We used site-directed fluorescence probing to map part of the region of soluble TF (sTF) that interacts with FXa in sTF–FVIIa–FXa–TFPI. . | Eur. J. Biochem. 270 2576-2582 2003 FEBS 2003 doi Probing the interface between factor Xa and tissue factor in the quaternary complex tissue factor-factor Vlla-factor Xa-tissue factor pathway inhibitor Karin Carlsson1 Per-Ola Freskgârd2 I Egon Persson3 Uno Carlsson1 and Magdalena Svensson1 1IFM-Department of Chemistry Linkoping University Linkoping Sweden 2Protein Biotechnology Novo Nordisk A S Novo Alle Bagsverd Denmark 3Haemostasis Biology Novo Nordisk A S Novo Nordisk Park Malav Denmark Blood coagulation is triggered by the formation of a complex between factor VIIa FVIIa and its cofactor tissue factor TF . TF-FVIIa is inhibited by tissue factor pathway inhibitor TFPI in two steps first TFPI is bound to the active site of factor Xa FXa and subsequently FXa-TFPI exerts feedback inhibition of TF-FVIIa. The FXa-depend-ent inhibition of TF-FVIIa activity by TFPI leads to formation of the quaternary complex TF-FVIIa-FXa-TFPI. We used site-directed fluorescence probing to map part of the region of soluble TF sTF that interacts with FXa in sTF-FVIIa-FXa-TFPI. We found that the C-terminal region of sTF including positions 163 166 200 and 201 is involved in binding to FXa in the complex and FXa most likely via its Gla domain is also in contact with the Gla domain of FVIIa in this part of the binding region. Furthermore a region that includes the N-terminal part of the TF2 domain and the C-terminal part of the TF1 domain . the residues 104 and 197 participates in the interaction with FXa in the quaternary complex. Moreover comparisons of the interaction areas between sTF and FX a in the quaternary complex sTF-FVIIa-FXa-TFPI and in the ternary complexes sTF-FVII-FXa or sTF-FVIIa-FX demonstrated large similarities. Keywords fluorescence local probing protein-protein interactions site-directed labeling. Complex formation between factor VIIa FVIIa and its cofactor tissue factor TF triggers blood coagulation. The TF-FVIIa complex activates .